Biochemistry

Biochemistry
Aaser Abdelazim
Professor of Medical Biochemistry and Molecular Biology
FAIMER fellow 2021 (Medical Education)
Clinical Biochemistry Consultant
aaserabdelazim@yahoo.com
8/15/23 1
Aaser Abdelazim _ Medical Biochemistry

Part 1
Carbohydrates chemistry
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1. General view of carbohydrates
2. Functions of carbohydrate
3. Classification of carbohydrates
4. General properties of carbohydrate
5. Monosaccharides
6. Disaccharides
7. Polysaccharides

8/15/23 Aaser Abdelazim _ Medical Biochemistry 3
CARBOHYDRATES
(A) General view on CARBOHYDRATES
Aldehyde
Ketone
Contains carbon and water
Soluble in water
Sweetly Energy

(1) Primary source of energy (brain and RBCs)
DNA and RNA (Nucleosides and nucleotides)
Gangliosides
Carbon skeleton of amino acids
(2) Structure bases of major chemicals
(3) Principle part of cell membrane structure
(4) Intracellular messenger
Each gm gives 4 Kcal of energy
(average daily requirements of energy = 1800-2300 kcal/day)
CARBOHYDRATES
4
(B) FUNCTIONS OF CARBOHYDRATES
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(5) Enters in the structure of cell receptors

(C) CLASSIFICATION OF CARBOHYDRATES
Monosaccharide Disaccharides Oligosaccharides
Carbohydrates
Polysaccharides
Carbohydrates contains 3-
10 units of
monosaccharides.
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Reducing
Non-reducing
Aldoses
Ketoses
Homopolysaccharides Heteropolysaccharides

(a) MONOSACCHARIDES
Glyceraldehyde Dihydroxyacetone
qMonosaccharides consists of single polyhydroxy aldehyde or ketone unit which cannot be
broken down to simpler substances on acid hydrolysis.
qThey are also called simple sugars.
qMonosaccharides are further divided into:
i. Aldoses, i.e. Aldo sugars (all are from glyceraldehyde)
ii. Ketoses, i.e. Keto sugars (all are from dihydroxyacetone)
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Points Aldoses Ketoses
Functional group Aldehyde Ketone
Classes According to the number of carbon
atoms in the sugar
According to the number of carbon
atoms in the sugar
Suffix Ended by –ose Ended by –ulose
Reference sugar Glyceraldehyde Dihydroxyacetone
Examples Triose, tetrose, pentose, hexose Triulose, tetrulose , etc

Carbon# Sugar Aldoses Ketoses
3 C Trioses glyceraldehyde (aldotriose) Dihydroxy acetone
(ketotriose)
4 C Tetroses Erythrose (aldotetrose) Erythrulose
5 C Pentoses qRibose (aldopentose)
qDeoxyribose (aldopentose)
qXylose (aldopentose)
Xylulose (ketopentose)
6 C Hexoses qGlucose
qGalactose
qMannose (aldohexose)
Fructose (ketohexose)
7C Heptoses pseudoheptose Pseudoheptulose
ALDO AND KETO SUGARS
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(A) TETROSES
Aldoses Ketoses
Erythrose
(B) PENTOSES
Ribose
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Erythrulose
Ribulose
Structure of monosaccharides

(C) HEXOSES
Aldoses Ketoses
Erythrose
(D) HEPTOSES
Heptose Heptulose
Glucose Fructose
8/15/23 9

HOW WE CAN SKETCH A MONOSACCHARIDE?
Open chain formula
Haworth projection formula
(a) Pyran formula
Fischer's formula
1
2
3
4
5
6
1
2
3
4
5
6
1
2
3
4
5
6
C
C
C
C
C
1
2
3
4
5
6
Haworth projection formula
(b) Furan formula
Chair formula
1
2
3
4
5
6
Boat formula
1
2
3
4
5
6
OH
C
H
H
C
OH
α β

GENERAL PROPERTIES OF MONOSACCHARIDES
Physical properties Chemical properties
q State Solution
q Solubility In water
q Taste Sweety
q Odor Odorless
q Color Colorless
q Precipitation Not form ppt
q Reaction Neutral
q Asymmetric C ?
Sugar derivate Reaction Product
Sugar alcohol Reduction Sorbitol
Sugar acids Oxidation 1.Gluconic (C1)
2.glucaric
(saccharic)(C1,6)
3.glucouronic (c6)
Amino sugar Amination Hexosamine
Amino sugar
acids
Oxidation &
amination
Neuraminic acid
Deoxy sugar Deoxygenation Deoxyribose
Glycosides Glycosidic linkage
formation (O and
N linkages)
qGlycolipids
qGlycoproteins
qSugar phosphates
qDisaccharides
Glycosidic linkage
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Asymmetric carbon atom
üCarbon atom attached to 4 different functional groups.
üAny compound contain this carbon it will show 4 properties.
Glyceraldehyde
Aldehyde
Hydroxyl
Alcohol
Hydrogen
Asymmetric
carbon
Optical
activity
Isomerism Mutarotaion αor β forms
üLevorotatory
üDextrorotatory
üRacemic mixture
ü# of isomers= 2n
ün is the # of
asymmetric carbons
üChange in the
specific rotation angle.
üForms a and B
anomers.
8/15/23 12
OH
C
H

Quizzes on carbohydrates chemistry (monosaccharides)
1. The father sugar of glucose is:
a. Glyceraldehyde
b. Dihydroxyacetone
c. Glycerine
d. Glycone
2. All aldo-sugars are ended by suffix:
a. -ose
b. -ulose
c. -one
d. -ol
3. The largest natural occuring monosaccharide in human body contains:
a. Three carbons
b. Five carbons
c. Seven carbons
d. Nine carbons
4. The reference sugar of glucose is:
a. Glyceraldehyde
b. Dihydroxyacetone
c. Glycerine
d. Glycone
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5. Disaccharides can be known as:
a. Multisaccharides
b. Oligosaccharides
c. Polysaccharides
d. Monosaccharides
6. Give the name of the following sugar.
a. Mannose
b. Fructose
c. Glucose
d. Heptose
7. The optically active sugar is the sugar which:
a. Contains amino group
b. Contains carbon atoms
c. Rotate the polarized light
d. Present in alpha anomer
8. Which of the following is belonging to chiral carbon?
a. Attached to two different groups
b. Attached to asymmetric carbon
c. Attached to hydroxyl groups
d. Attached to four different groups
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9. Racemic mixture is the mixture that contains:
a.Two different optically active sugars
b.Two levorotatory sugars
c.Two dextrorotatory sugars
d.Two optically inactive sugars
10. The mutarotation is the mutation of :
a. Rotation angle of optically active sugars
b. Isomers of optically active sugars
c. Anomers of active sugars
d. Carbon atoms numbers of sugars
11. Which of the following is related to Haworth projection formula for monosaccharides?
a. Open chain formula
b. Fischer's formula
c. Chair formula
d. Pyran formula
12. In the furan ring of Haworth projection formula the ring is
a. Six edges
b. Seven edges
c. Five edges
d. Four edges
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13. Sorbitol is derived from sugars through:
a.Reduction
b.Oxidation
c.Amination
d.Deoxygenation
14. Glucaric acid can be obtained from glucose through oxidation of:
a. Alcohol group of first carbon
b. Alcohol group of last carbon
c. Alcohol group in first and last carbons
d. Alcohol group in 2nd carbon
15. Which of the following is the glycosidic linkage used to join two monosaccharides?
a.O'glycosidic linkage
b.N'glycosidic linkage
c.L'glycosidic linkage
d.D'glycosidic linkage
8/15/23 16

(b) DISACCHARIDES
qThey are two monosaccharides joined together by
glycosidic linkage
qReducing disaccharides (lactose and maltose), Non-
reducing (sucrose).
qTheir properties are the same like monosaccharides
Disaccharides
Glycosidic linkage
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Sucrose
(1) SUCROSE
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üContents : glucose & fructose
üLinkage:1,2 α glycosidic linkage
üSource: cane, beet, fruits,
vegetables.
üNonreducing sugar not forms
osazone and does not exhibit
mutarotation.
üWhat is the difference between
sucrose and invert sugar?

Sucrose and invert sugar
Points Sucrose Invert sugar
Synonyms Table sugar –cane sugar Honey sugar
Source Beet, cane, fruits, vegetables. Bee honey
Composition α-glucose with β-fructose linked
together with 1,2 glycosidic linkage
Equimolar mixture of α-glucose and
β-fructose
Optical activity Dextrorotatory (+66.5°) Levorotatory (-20.5°)
Sweetness Less sweeter than invert sugar 30% more sweeter than sucrose.
Reduction Non-reducing sugar Reducing sugar (free CHO/ C=O
groups)
Digestion By sucrase No need for digestive enzymes
Inversion Can be inverted by heating with
acids or by digestive enzymes as
sucrase.
Ca not be inverted

(2) LACTOSE
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üContents : galactose &glucose
üLinkage: 1,4 β glycosidic linkage
üSource: milk, pharmaceutical
preparations.
üHuman milk contains 74% lactose
üReducing sugar
üShows mutarotation
üLactose intolerance: due to lactase
deficiency in adults inducing diarrhoea,
flatulence and dehydration . Can be
controlled by lactase pills or yoghurt as a
alternative source for Ca.
Lactose

LACTULOSE
üContents : galactose &fructose
üLinkage: 1,4 β glycosidic linkage
üSource: heated milk, synthetically
produced
üCan not be hydrolyzed by intestinal
enzymes.
üFermented by intestinal bacteria.
üCan be used as mild diuretic and osmotic
laxative.
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Medicinal uses of Lactulose
1. As a synthetic sugar used to treat constipation. It is broken down in the colon
into products that pull water out from the body and into the colon. This water
softens stools.
2. Lactulose is also used to reduce the amount of ammonia in the blood of
patients with liver disease.
Sweetness index

Maltose
(3) MALTOSE
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üContents : glucose &glucose
üLinkage: 1,4 α glycosidic linkage
üSource: malt, germinating cereals and
enzymatic hydrolysis of starch
üHydrolyzed by maltase enzyme into
glucose.
üIt is the major product of starch
breakdown
üIt is a reducing disaccharide.
üShows mutarotation
üForms sunflower shape osazone.

(4) ISOMALTOSE
ü Two units of ℬ-glucose connected by ℬ1,4 glyosidic
linkage.
ü Its origin is the hydrolysis of cellulose.
(5) CELLOBIOSE
ü Two units of ⍺-glucose connected by ⍺1,6 glyosidic
linkage.
ü Its origin is the hydrolysis of starch.
(6) TREHALOSE
ü Two units of ⍺-glucose connected by ⍺1,1 glyosidic
linkage.
ü Present in fungi and yeast.
ü The major sugar of insect hemolymph.
Other disaccharides

(C) OLIGOSACCHARIDES
Ø Sugar units formed from 3-10 units of monosaccharides.
Ø These units of sugars can bind to lipids (glycolipids) or proteins (glycoproteins).
Ø Many oligosaccharides also can be present in diet.
N-linked oligosaccharides
O-linked oligosaccharides
Dietary oligosaccharides
1) Fructo-oligosaccharides (FOS): polymers of fructose but less than inulin present in many
vegetables.
2) Galacto-oligosaccharides (GOS): consist of polymers of galactose.
3) Mannan-oligosaccharides (MOS): have role in immunomodulation.

(D) POLYSACCHARIDES
8/15/23 25
• Store
form of
energy
• Ended by
suffix (an)
• Non-
reducing
sugars
• Polymers
Monosaccharides
connected to
each others by
glycosidic linkages
Due to absence of
free carbonyl
groups and long
chains
hydrocarbons
Stored inside the
body to be used
as a source of
glucose release
Fructosans
Glycans
Mannans

Classification of polysaccharides
Homopolysaccharides Heteropolysaccharides
Starch
Glycogen
Cellulose
Dextrin
Inulin
Hyaluronic acid
Heparin
Chondrotin
Dermatan
Keratan

(1) STARCH
(a) Amylose part
(b) Amylopectin part
(1)Homopolysaccharides
8/15/23 27
Its molecular weight varied from few thousands to millions.
The branching point occuring every 24-30 residues.

(1) STARCH
1. Plants store glucose in the form of
starch.
2. The general formula of starch is similar
to that of glucose (C6H10O5)n.
3. They are heavy hydrated molecules.
4. Most abundant in tubers like potato and
seeds.

(2) GLYCOGEN
Straight linear chain
Branching point
8/15/23 29
ü It is similar to amylopectin in the structure. but glycogen is more extensively branched (on average,
every 8 to 12 residues) and more compact than starch.
ü It abundant in liver (7% of wet weight of liver), and also stored in skeletal muscles.
ü Why liver cells not store glucose as it is?
Ø First to keep cell osmolarity as glucose if stored iside the cells will drain water inside and leading to
cell rupture
Ø Second presence of high glucose inside the cell will lead to increase energy needed to transport more
glucose against conc gradients which will be prohibitively large.

(3) CELLULOSE
It is a polymer of B-glucose linked by (1,4) glycosidic linkage
(4) DEXTRIN
o Partial hydrolytic products of starch formed from amylose
part or amylopectin part.
o So they may be linear (amylose) or branched (amylopectin).
o They also carry free carbonyl group so can reduce alklaine
cupper sulphate.
8/15/23 30
o Cellulose, a fibrous, tough, water-insoluble substance, is found
in the cell walls of plants, particularly in stalks, stems, trunks,
and all the woody portions of the plant body.
o Cellulose molecule is a linear, unbranched homopolysaccharide,
consisting of 10,000 to 15,000 D-glucose units.
o Human cannot use cellulose as a fuel source, because they lack
an enzyme to hydrolyze the (ℬ1,4) linkages.
(5) CHITIN
o is a linear homopolysaccharide composed of N-
acetylglucosamine residues in ℬ- linkage.
o Chitin forms extended fibers similar to those of cellulose, and
like cellulose cannot be digested by vertebrates.
o Chitin is the principal component of the hard exoskeletons of
nearly a million species of arthropods—insects, lobsters, and
crabs, for example— and is probably the second most abundant
polysaccharide, next to cellulose, in nature.

(6) INULIN
o Fructosan, formed from repeated units of fructose connected
with B-1,2 glyosidic linkage.
o Present in the roots of artichokes and other plants.
o Medical importance: it used in the diagnostic test for kidney
functions (inulin clearance test)
Inulin structure

(2) Heteropolysaccharides
8/15/23 32
üRepeated units of amino sugar and acid sugar
ü It called glycosaminoglycans (GAGs)or mucopolysaccharides or (proteoglycans).
B-D- Glucuronic acid B-L- Iduronic acid

Heparin
Chondroitin sulfate
Hyaluronic acid
Keratan sulfate

Glucuronic acid N-acetyl galactosamine Iduronic acid N-acetyl galactosamine
Chondroitin sulfate vs dermatan sulfate

GAGs member Structure Site Function
Hyaluronic acid B-glucuronate + N-acetyle
glucosamine linked by β(1, 3)
Synovial fluids- Vitrous body
of the eye. Embryonic tissue-
cartilage and loose
connective tissue.
Ø Absorb concussion.
Ø Make C.T. loose.
Ø Aid in migration of cells in
embryo life.
Ø Lubricant to joints.
Chondroitin 4-
and 6-sulfates
B-glucuronate + N acetyle
galactosamine-4- or 6-sulfate
linked by β(1, 3)
Cartilages, tendons, ligaments
and bones
Aorta, skin, cornea, umbilical
cord and certain neurons.
ØMaintain the shape of skeleton
ØBinds with collagen make
cartilage strong
ØCompress cartilage for weight
bearing.
Heparin and
heparin sulphate
Glucouronic or Iduronate-2-
sulfate + N-sulfo-D-glucosamine-
6-sulfate linked by α(1, 4).
Mast cells (cell wall of blood
vessels of liver, lungs, skin,
heart, kidneys and spleen)
Anticoagulant
Heparan sulfates The same structure as heparins
although, heparans have less
sulfate than heparins and
contains GlcNAc instead of
glucosmaine.
Extracellular matrix and cell
membrane
Ø Cell to cell adhesion
Ø Structure of basement
membrane
Ø Cell membrane receptors
Ø Role in cell-to-cell interactions.
Keratan sulfates Galactose + GlcNAc-6-sulfate
linked by β(1, 4)
Cornea and cartilages Keeps Corneal transparency
Dermatan sulfates L-iduronate + N-acetyl galactose
amine-4-sulfate linked by β(1, 3)
Cornea, sclera, skin, blood
vessels, heart valves.
ØMaintain the shape of the eyes
ØKeep corneal transparency
8/15/23 35
Glucose amino glycans (GAGs)

Points Proteoglycans Glycoproteins
Structure Core Protein attached to one or more chain of
GAGs (test tube brush -like)
Proteins covalently attached to oligosaccharides
(usually monosaccharides units)
Location Connective tissue and extracellular matrix Cell surfaces and extracellular matrix
Carbohydrate
contents and %
qMore than 50 units (Heteropolysaccharides)
qRepresents about 50-60% of the structure.
q2-15 units of monosaccharides(Galactose,
Mannose, sugar amines, pentoses).
qRepresents 10-15% of the all structure.
Charge Carbohydrate chains are negative (–ve) charged
due presence of glucuronic or iduronic acids.
Could be Charged or not
Chains Long chains with protein in core Short chains
Classes Based on the type of GAGs, (multiple GAGs could
be present).
Only two types O-linked glycoproteins and N-
linked.
Significance Support function (Absorb water and act as
cushion for cartilages).
Function modifications (proteins are modified
through the change in glycosylation processes.
Types Chondroitin- sulfate, dermatan, Heparan,
Keratan, heparin and Hyaluronic acid.
Collagens, mucins, transferrin, immunoglobulins,
antigens, blood group determinants, hormones
etc..
Functions q Cell to cell interaction and adhesion.
q Support the structure of tendons, ligaments
and bones.
qCell to cell recognition and cell signaling.
qBlood groups
qCell receptors
qSome hormones and enzymes
qImmunoglobulins
qMucin
Proteoglycans vs glycoproteins

Quizzes on carbohydrates chemistry (disaccharides)
1. The glycosidic linkage in sucrose is:
a. α1,2
b. β1,2
c. α1,4
d. β1,4
2. All aldo sugars are ended by suffix:
a. -ose
b. -ulose
c. -one
d. -ol
3. The largest natural body contains:
a. Three carbons
b. Five carbons
c. Seven carbons
d. Nine carbons
4. The glucose is:
a. Glyceraldehyde
b. Dihydroxyacetone
c. Glycerine
d. Glycone
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Part 2
Lipids chemistry
8/15/23 38
1. General view on lipids
2. Lipids classification
3. Fatty acids
4. Triglycerides
5. Compound lipids
6. Derived lipids

Functions of lipids
high energy value (1 gm of lipids gives
9KCal).
they act as thermal insulator.
enter in the structure of cell membranes
act as fixative for internal organs.
Properties Lipids
Organic compounds
composed of fatty acid
Not soluble in water but
soluble in fat solvents as
ether, chloroform, benzene
They are hydrophobic
compounds
(A) Genral view on lipids

(C) Lipid classification
Simple lipids Compound lipids Derived lipids
Lipids
qPhospholipids
qGlycolipids
qLipoproteins
qSulpholipids
qFatty acids
qSteroids
qFat soluble vitamins
qCarotenes
qKetone bodies
qTerpenes
8/15/23 40
Waxes
Neutral
fats/triglycerides

Neutral fats/triglycerides
Glycerol Fatty acid1
Fatty acid 2
Fatty acid 3
Glycerol
Fatty acid1
Fatty acid 2
Fatty acid 3
Simple triglyceride
Mixed triglyceride

ü Human wax:
1. Wax present in human blood cholesteryl palmitate.
2. These are esters ester of cholesterol and palmitic acid. Apart from blood plasma, these
are also found in suprarenal and sebaceous glands.
ü Animal wax
1. The best known animal wax is beeswax used in constructing the honeycombs of
honeybees,
2. A major component of the beeswax is myricyl palmitate
Waxes
Alcohol
Fatty acid
• Organic compounds
• Lipophilic
• Its melting temperature is > 40 ºC
• Soluble in fat solvents
Cholesteryl palmitate
Myricyl palmitate

FATTY ACIDS
q☞Long chain monocarboxylic aliphatic compounds.
q☞All fatty acids are containing free COOH group and terminal CH3 group.
q☞May be odd /even fatty acids (according to # of carbons).
q☞They may be saturated (no double bond) or unsaturated (one (monounsaturated) or more
(polyunsaturated) double bonds).
q☞They may be of short or long chains, Short chain fatty acids are water soluble-long chain one fat
soluble.
Fatty acid structure
8/15/23 43
Carboxyl group
Last methyl group (ώ)(omega carbon)

FATTY ACIDS
Saturation
Saturated Unsaturated
Monounsaturated Polyunsaturated
Nutrition
Essential Nonessential
8/15/23 44
-anoic -enoic

Common name Number of C Sources
Formic 1 Role in the metabolism of one carbon unit
compounds
Acetic acid 2 Originate form the metabolism of
carbohydrates in large animals rumen
Propionic acid 3 Carbohydrates fermentation in rumen
Butyric acid 4 Certain fats like butter
Valeric acid 5 Certain fats like butter
Caproic acid 6 Certain fats like butter
Caprylic acid 8 Fats of plant origin
Capric acid 10 Fats of plant origin
Lauric acid 12 Palm, cinnamon, coconut, laurels
Myristic acid 14 Nutmeg, palm, kernel, coconut, oils,myrties
Palmitic acid 16 Common in all animals and plant fats
Stearic acid 18 Common in all animals and plant fats
Arachidic 20 Peanut (arachis) oils
Behenic acid 22 Seeds
Lignoceric acid 24 Cerebrosides , and peanut oil
Saturated fatty acids

Unsaturated fatty acids
8/15/23 46
Common name Number of C and
position of double
bonds
Omega series Occurrence
Palmitoleic C16: 1: Δ9 ώ7 All fats
Oleic C18: 1: Δ9 ώ9 The most common fatty acid in natural
fats
Elaidic C18: 1: Δ9 (trans) ώ9 Hydrogenated and ruminant fats
Erucic C22: 1: Δ13 ώ9 Rape and mustard seed oil
Nervonic C24: 1: Δ15 ώ9 Cerbrosides
Linoleic C18: 2: Δ9,12 ώ6 Corn, peanut, cotton seed, soyabean,
and many plant oils
Gamma-
Linolenic
C18: 3: Δ6,9,12 ώ6 Some plants like oil of evening primrose-
minor in animals
⍺-Linolenic C18:3: Δ9,12,15 ώ3 Linseed oil
Arachidonic C20:4: Δ4,5,8,11,14 ώ6 Peanut oil very important for human
phospholipids
Timnodonic C20:5: Δ5,8,11,14,17 ώ3 Fish oil and cod liver oil
Clupanodonic C22:5: Δ7,10,13,16,19 ώ3 Fish oil and phospholipids of brain
Cervonic C22:6: Δ4,7,10,13,16,19 ώ3 Fish oil and phospholipids of brain

Delta (Δ) numbering
Omega (ώ) numbering
Numbering system for unsaturated fatty acids
CH3-CH=CH-CH2-CH2-CH2-CH2-CH2-CH2-CH2-COOH
1 2 3 4 5 6 7 8 9 10 11
11 10 9 8 7 6 5 4 3 2 1
C11:1: Δ9
C11:1: ώ 2

Numbering system for unsaturated fatty acids
Delta (Δ)
Omega
(ώ)
Fatty acid Number Description
Palmitoleic C16: 1: Δ9 contains 16 carbon
atoms and have one
double bond between
C9 and C10
Linoleic C18: 2:
Δ9,12
?
Linolnic C18: 3:
Δ9,12,15
?
Arachidonic C20: 4:
Δ5,8,11,14
?
Fatty acid Number Description
Palmitoleic C16: 1 ώ7 contains 16
carbon atoms and
have one double
bond The double
bond on the C7
counting from ώ-
carbon.
8/15/23 48

Cis and Trans forms of double bonds
C = C
H
H
C = C
H
H
Cis form
Trans form
Cis-oleic acid
Trans-oleic acid
8/15/23 49

TRIGLYCERIDES
qThese are compound formed from glycerol esterifies by 3 fatty acids.
qIts sources include (animal, butter and ghee; plant, cotton seed oil, olive seed oil, linseed oil;
marine, cod liver oil and shark oil).
TRIGLYCERIDES
Simple Mixed
qThe three fatty acids are the
same as triolein
8/15/23 50
qThe three fatty acids are different
e.g distearinpalmitin

General properties of triglycerides
Chemical properties
q Solubility In soluble in water but soluble in Fat solvents.
q Melting point • TAGs rich in unsaturated FAs (OILS) are liquids
• TAGs rich in saturated `FAs (FATS) are solid.
q Specific gravity Less than water [they can float on the surface of water]
q Odor Odorless
q Color Colorless (yellow butter is due to carotenes)
q Taste Tasteless
8/15/23 51
Physical properties
(a) Physical properties

Reaction Products
Acrolein test All TAGs are containing glycerol so they positive for acrolein test.
Hydrolysis (Lipases) Digestive lipases breakdown TAGs in to Free fatty acids and glycerol
Saponification
(Reaction with alkalies)
Alkalies can react with TAGs breaking them to Glycerol and sodium or
potassium salt of fatty acid e.g sodium palmitate (soap).
Soaps can emulsifying fatty materials as they split large fat molecules
into small ones.
Hydrogenation
(Hardening of oils)
Addition of Hydrogen to unsaturated fatty acids at high temperature in
presence of nickel as catalyst to produce saturated fatty acids(convert oil
to fats).
(Oils) (fats)
Halogenation Halogens as iodine can saturate the double bonds of unsaturated fatty
acids present in oils.
(b) Chemical properties
- CH=CH-
I2
- CH-CH-
I I
I I
- CH=CH-
H2
- CH-CH-
I I
H H
Ni + △

Oxidation
(Rancidity)
Rancidification
It is change in the odor, taste and color of fats and oils produced by oxygen,
bacteria and moisture.
•Oxidative rancidity: fatty acids are oxidized at double bonds to give (peroxide
radicals)
•Ketonic rancidity: (Ketones & Aldehydes)
•Hydrolytic rancidity: (FAs & glycerol)
R- CH=CH-COOH - CH-CH-
I I
O O
-
R- CH=CH-COOH
R-CHO
II
O
R-C- CH2-COOH
(Aldehyde)
(Ketone)
CH2-OH
CH- OH
CH2-OH
I
I
+ 3 R-COOH
(Triglycerides) (Glycerol) (fatty acids)

Fat constants
Constant/number/value Definition and significance
Saponification number Definition: Mg of KOH needed to saponify all fatty acids present in
one gram of fat.
Significance: Fats contain high % of short chains Fatty acids have
greater saponification number than that of high % of long chain fatty
acids.
Acid value Definition: Mg of KOH needed to neutralize free fatty acids present in
one gram of fat.
Significance: it is very important to detect the degree of rancidity.
Normal acid value is zero for fats it starts to increase after rancidity
due to production of free fatty acids.
Iodine number Definition: grams of iodine needed to saturate unsaturated fatty
acids present in 100 gram of fat.
Significance: give an idea about the degree of unsaturation of fatty
acids present in fats.
Acetyl number Definition: mg of KOH needed to neutralize acetic acid of one gram
of acetylated fat.
Significance: important for detection the presence of hydroxy fatty
acids.

Comparison between triglycerides and waxes
Point Triglycerides Waxes
Composition Glycerol and 3 fatty acids Alcohol rather than glycerol
and one fatty acid
Acrolein test Positive Negative
Digestion by lipases Digested by lipases Not digested
Utilization Utilized by body cells Not utilized
Melting point Solid or liquid at RT Solid at RT
Rancidity Undergo rancidity Do not undergo rancidity
Storage Stored in fat stores as
adipose tissue
It is Present usually
extracellularly as in blood or
sebaceous secretions
Nutritional value Has a great nutritional
value
Has not nutritional value

COMPOUND LIPIDS
Phospholipids
Sphingophospho
lipids
Glycerophosphol
ipids
Phosphatidic acid
Lecithin
Cephalins
Lipositol
Cardiolipin
Lysophospholipids
Plasmalogens
Sphingomyelins
Glycolipids
Cerebrosides
Gangliosides
Sulfolipids
Lipoproteins
VLDL
IDL
LDL
HDL
Chylomicrons
FFAs+albumin
8/15/23 56

(1) Phospholipids
(a) Glycerophospholipids
Glycerol
Fatty acid
Fatty acid
Fatty acid P Base
N
I
I
I
CH3
CH3
I
CH3 OH
Choline
CH2
I
CH2
I OH
I
NH2
Ethanolamine Inositol
CH2
I
CH2
I
COOH
I
NH2
I
OH
Serine

Glycerol
Fatty acid
Fatty acid
Fatty acid P Base
Phosphatidic acid
Choline
Lecithins
Serine
cephalins
Inositol
Lipositol
Ethanolamine
Plasmalogen
Choline _fatty acid
Lysophospholipids
Ethanolamine
8/15/23 58

Cardiolipin
ü Two phosphatidic acid in between one glycerol
ü 4 fatty acids
8/15/23 59
a

X= Ethanolamine
Plasmalogen
a
ü Phosphatidic acid
ü 3 fatty acids
ü Fatty acid attached to the first carbon by ether bond not ester bond.

Functions of glycerophospholipids
Member Functions
q Phosphatidic acid Is an important intermediate in synthesis of all glycerophospholipids.
q Lecithins 1. Enter in the structure of cell membranes.
2. It act as a body store for choline.
3. Plays a role in digestion and absorption of fats.
4. Dipalmityl lecithin: it acts as lung surfactant. Very important for
the expansion of lung alveoli after birth. Premature babies
produce less amount of surfactant which may lead to lung
alveolar collapse. The amount of lung surfactant used to
determine the date of birth.
q Cephalins 1. Formation of biological membranes.
2. Formation of thromboplastin (coagulation mechanism).
q Lipositol Act as a second messenger mediating hormone action
q Cardiolipin Is a Major Lipid of Mitochondrial Membranes
q Lysophospholipids Derivative of phospholipids
q Plasmalogens Constitute 10% of the phospholipids of brain and muscle.
8/15/23 61

(b)Sphingophospholipids
Sphingosine
(1) Sphingomyelin:
Present with high amount in brain and
nerve tissues
ü Sphingosine
ü Fatty acid
ü Phosphate
ü Choline base
8/15/23 62
(2) Ceramide:
As it is not a phospholipid but it formed from
ü Sphingosine
ü Fatty acid
Fatty acid
Sphingosine

(a) Cerebrosides (simple glycolipids)
Fatty acid
Sphingosine
Carbohydrate
Glucose
Galactose
Glucocerebrosides
Galactocerebrosides
Cerebrosides Fatty acid type Function
Nervon Nervonic acid (24 C) 1. Constituted in brain tissues
mainly in myelin of nerve fibers.
2. They act as insulator of nerve
cells.
Oxynervon Oxynervonic acid
Cerebron Cerebronic acid (C24)
Kerasin Lignoceric acid (24C)
8/15/23 63
(2) Glycolipids
Types of cerebrosides

(b)Gangliosides: (complex glycolipids)
Fatty acid
Sphingosine
Glucose
Galactose
NANA
N-acetyle
glucoseamine
Gangliosides functions
1.Act as receptors on cell membrane
2.Constituted in brain tissue with high
percentage.
N.B
ü All hexoses number is = 3
ü There are one or more molecule of
NANA.
Fatty acid
Sphingosine
Galactose
Sulphate
(c)Sulpholipids
8/15/23 64
Creamide Sialic acid

Core (Polar lipids)
Shell 2nm thick
(Amphipathic lipids)
Structure
8/15/23 65
(3) Lipoproteins

Proteins to lipid contents of lipoproteins:
Chylomicrons
Protein
Fat
HDL
(good)
LDL
(bad)
VLDL
High protein, low fat Low protein, high fat
8/15/23 66

Lipoprotein class Density
(g/ml)
Diameter (nm) Protein (%) of
dry weight
Phospholipids
(%)
Triacylglycerol (%)
of dry weight
Chylomicrons < 0.95 100-500 1-2 7 84
VLDL 0.95-1.006 30-80 10 18 50
IDL 1.006-1.019 25-50 18 22 31
LDL 1.019-1.063 18-28 25 21 4
HDL 1.063-1.21 5-15 33-50 29 8
Lipoproteins classes
8/15/23 67

DERIVED LIPID
qThey are substances which are associated with lipids in nature, and related to
them in properties and metabolism.
Steroids
Fatty acids
Glycerol
Alcohols
Ketone
bodies
Eicosanoids
Carotenoids
DERIVED LIPID
8/15/23 68

Steroids
Steroid nucleus
q Steroids are compounds contain steroid nucleus.
q steriod nucleus (cyclopentanperhydrophenantherine)
q The most important steroids are
- Cholesterol
- Ergosterol.
- Vitamin D.
- Bile salts.
- Steroid hormones.
- Digitalis glycosides.
8/15/23 69

Cholesterol
qOne of the most sterols present in the body derived from
steroid nucleus and contain OH group.
q Distribution in the body:
1.Cholesterol is widely distributed in nervous tissue, adrenal
cortex, liver and kidneys.
2.It is a major constituent of the plasma membrane and
plasma lipoproteins.
3.Present in blood in 2 forms
üFree form
üEsterified form(combined to fatty acid)
Its level normally 220 mg/dl
Structure:
osteroid nucleus
oOH group at C3
o2 methyl group at C10 and C13
oLong side chain at C17
oAll # of carbons = 27
8/15/23 70

QUIZ on Carbohydrates and lipids chemistry
1. Which of the following is a non-reducing disaccharide?
a) Fructose
b) Sucrose
c) Galactose
d) Glucose
2. Which about glucose is true?
a) It is a disaccride.
b) It is a monosacchride
c) It is a polysacchride
d) It is an oligosachride
3. Sucrose is composed of-----------------
a) Glucose and Fructose
b) Glucose and Maltose
c) Mannose and Trehalose
d) Galactose and Mannose
4. Which one is NOT a homoplysacchride?
a) Starch
b) Glycogen
c) Cellulose
d) Heparin
5. Which one is fructosan in nature?
a) Strach
b) Inulin
c) Cellulose
d) Glycogen
8/15/23 71

6. Choose the sugar which abundant present in honey?
a) Fructose
b) Mannose
c) Galactose
d) Lactose
7. Which one is an aldo-pentose?
a) Mannose
b) Ribose
c) Ribulose
d) Erythrose
8. Choose the keto-tetrose?
a) Ribulose
b) Fructose
c) Erythrose
d) Erythrulose
9. Which one is a heteropolysaccharide?
a) Chondritin
b) Carnitine
c) Creatine
d) Keratin
10. Which one is a keto hexose?
a) Fructose
b) Glucose
c) Mannose
d) Galactose

11. Choose the polysaccride formed by α1-4 glycosidic linkage?
a) Amylose
b) Amylopectin
c) Inulin
d) Cellulose
12. Choose the correct formula of glucose?
a) C6H12O12
b) C6H12O6
c) C6H6O12
d) C12H12O6
13. Which one id the storage form of glucose in plant?
a) Cellulose
b) Glycogen
c) starch
d) Agar
14. Which one is have not a nutritional value?
a) Starch
b) Glycogen
c) Cellulose
d) Dextrin
15. All the following about polysaccharides is true except?
a) They are formed from a repeated units of sugars.
b) They can be used as atorage for energy.
c) Consisted of a collections of amino acids.
d) Can be classified into homopolysacchrides and heteropolysacchrides.

16. Choose the storage form of lipids?
a) Triglycerides
b) Phospholipids
c) Cholesterol
d) Sulfolipids
17. Which one is monounsaturated fatty acid?
a) Oleic
b) Linoleic
c) Linolinic
d) Stearic
18. Choose the correct statement about fatty acid?
a) All fatty acids can be synthesized inside the body.
b) Fatty acid stored in the form of cholesterol inside cells.
c) The monounsaturated fatty acids are nonessential.
d) body can oxidizes only the saturated fatty acids.
19. Which one of the following forms of lipids mainly composed in the structure of cell membrane?
a) Triglycerides
b) Phospholipids
c) Ketone bodies
d) Cholesterol
20. Compound lipid is formed from-------
a) Triglycerides +glycerol
b) Triglycerides + carboydrates
c) Sphingolipids + glycerol
d) All are incorrect

21. Cholesterol is consisted in all the following except?
a) Sex hormones
b) Bile acids
c) Vitamin D
d) Cardiolipin
22. Which of the following have not glycerol in its structure?
a) Triglycerides
b) Phospholipids
c) Waxes
d) Cardiolipin
23. Arachidonic acid is polyunsaturated fatty acid contains --------------double bonds?
a) 4
b) 3
c) 2
d) 1
24. Glycerol is consisted in the structure of ------------------
a) Lecithins
b) Cardiolipin
c) Cerbrosides
d) Gangliosides
25. Which one of the following macromolecules is structurally diverse in the living world?
a) Lipids
b) Crabohydrates
c) Proteins
d) Ncleic acids

26. Generally the unsaturated fats are --------in room temperature.
a) Liquid
b) Solid
c) Semi liquid
d) Semisolid
27. Fats can be transported in the blood in which form?
a) Lipoproteins
b) Glycolipids
c) Triglycerides
d) Shingolipids
28. If the fatty acid is esterified with an alcohol of high molecular weight instead of glycerol, the resulting
compound is---------------------
a) Lipositol
b) Waxes
c) Triglycerides
d) Cephalin
29. A lipid is formed by the condensation of -----------------
a) Fatty acid and alcohol
b) Fatty acid and amino acids
c) Fatty acid and carbohydrates
d) Fatty acids and amines
30. Which one is a derived lipid?
a) Fats
b) Oils
c) Steroids
d) Waxes

31. Compounds formed from lipids along with carbohydrates is-----------
a) Neutral lipids
b) Waxes
c) Glycolipids
d) Phospholipids
32. Liquids form triglycerides at room temperature are called --------------
a) Fats
b) Oils
c) Waxes
d) Glycrides
33. Natural lipids are soluble in -------------------------
a) Water
b) Alcohols
c) Ether
d) Oils
34. Which one produces the highest number of ATPs?
a) Lipids
b) Carbohydrates
c) Proteins
d) Nucleic acids
35. Which one is a compound lipid?
a) Triglycerides
b) Lipoproteins
c) Cerbrosides
d) Cardiolipin

36. Carotenes are groups of compounds related to:
a) Neutral lipids
b) Derived lipids
c) Glycolipids
d) Phospholipids
37. Triglycerides can be soluble in:
a) Water
b) Alaklis
c) Acids
d) Ether
38. All triglycerides are solid at:
a) High temperature
b) Melting temperature
c) Freezing temperature
d) Room temperature
39. The specific gravity of triglycerides is:
a) More than water
b) Equal water
c) Less than water
d) Twice as water
40. Halogenation of lipids is:
a) Addtion of hydrogen
b) Addition of nickle
c) Addition of idoine
d) Addition of oxygen

41. Which one of the following types of rancidity aldehydes are formed?
a) Oxidative rancidity
b) Ketonic rancidity
c) Hydrolytic rancidity
d) Enzymatic rancidity
42. Soap is produced from triglycerides by:
a) Addition of soap
b) Addition of Salts of potassium and sodium
c) Adition of fatty acid salts
d) Addition of nickle
43. Phosphatidic acid is included in all glycerophospholipids except:
a) Plasmologen
b) Cardiolipin
c) Lysophosphatidic acid
d) Lecithens
44. Which one of the following contains the highest amount of phosphatidic acid?
a) Plasmologen
b) Cardiolipin
d) Lecithens
45. Lung surfactant contains high amount of:
a) Diplmotyl lecithens
b) Dioleyl lecithens
c) Distearyl lecithens
d) Dilinolyl lecithens

46. The most important significance of lung surfactant is:
a) A major structure of placenta
b) Prevents the collapse of lung alveoli
c) Enters in the structure of cell membrane
d) Included in the synthesis of thoromboplastin
47. Which one of the following glycerophospholipids is included in mitochondrial membrane?
a) Plasmologen
b) Lecithen
c) Cephalin
d) Cardiolipin
48. Choose the base included in cephalins?
a) Choline
b) Lipositol
c) Serine
d) Ethanolamine
49. By removal of one fatty acid from phosphatidic acid it will be:
a) Plasmologen
b) Cardiolipin
d) Lecithens
50. Which one of the following phospholipids is included in thromboplastin synthesis?
a) Lecithen
b) Plasmologen
c) Cardiolipin
d) Lipositol

51. Which one is a glycolipid?
a) Keratin
b) Keratan
c) Kerasin
d) Creatine
52. Which one of following bases present in sphingomylein?
a) Choline
b) Serine
c) Insitol
d) Ethylamine
53. Choose the lipoprotein contains the highest lipid contents?
a) LDL
b) HDL
c) VLDL
d) Chylomicron
54. Cholesterol contains ------------------carbons
a) 19
b) 25
c) 27
d) 29
50. Which is included in mitochondrial membrane?
a) Lecithen
b) Plasmologen
c) Cardiolipin
d) Lipositol

Part 3
Protein chemistry
8/15/23 82
1. Amino acids
2. Petides and peptide bond
3. Proteins structure and classification

Introduction
1. Proteins are the most abundant organic molecules in cells formed from amino acids
united together with peptide bond.
2. Amino acids> peptides> proteins
3. Amino acids in proteins arranged in what is called peptide chains.
4. If the amino acids number in chain more 50 the compound called protein, if the number
of amino acids less than 50 the compound called peptide.
5. Proteins functions are varied and different, transportation, immunity, enzymes formation,
buffers …
6. The amount of proteins present in adult body weighted 70 kg is 12 kg.
8/15/23 83

AMINO ACIDS
Definition: They are the structural units of proteins. Derived from fatty acids, which
have one or more substituted amino groups.
C
COOH
NH2
Ｈ
R
α-carbon
amino group
Carboxyl group
Hydrocarbon chain
Structure:
C
COOH
H2N Ｈ
R
D-amino acid
L-amino acid

Classification of amino acids:
Chemical classification Biological classification Metabolic classification
Neutral
Acidic
Basic
Essential
semi essential
Non-essential
Glucogenic
Ketogenic
Mixed

Classification of amino acids:
(1) Chemical classification
1.1. Neutral amino acids :
1.1.1. Neutral amino acids with aliphatic side chain.
Glycine
Alanine
Valine
Leucine
Isoleucine

1.1.2. Hydroxy containing amino acids:
Serine
Threonine
1.1.3. Sulfur containing amino acids:
Cysteine
Methionine

8/15/23 Aaser Abdelazim _ Medical Biochemistry
88
1.1.4. Aromatic amino acids:
Phenylalanine
Tyrosine
Tryptophan
1.1.5. Imino acids
Proline
Benzene ring
Phenol ring
Indole ring
Pyrrolidine ring

1.1.6. Amido acids :
Glutamine
Asparagine
1.2. Acidic amino acids:
Glutamate
Aspartate

1.3. Basic amino acids:
Arginine
Lysine
Histidine
Uredo group
Imidazole group
Tryptophan the largest amino acid = 11 C
Glycine the smallest amino acid = 2 C

(2) Biological classification
2.1. Essential amino acids
qAmino acids which cannot be synthesized in
the body so should be supplied in the diet.
qThey are (Isoleucine, Histidine, Tryptophan,
Valine, Threonine, Lysine, Phenylalanine,
Arginine, Leucine, Methionine).
[I Left Home To Make Visit Through Philipine Argntine ,
London]
2.2. Semi essential amino acids
qAmino acids which synthesized in the body
in amounts which are enough for adult person,
but not for growing child.
qThey are (Arginine & Histidine).
2.3. Non essential amino acids
Amino acids that can be synthesized in the
body and not need to be supplied in the diet.
The remain are non essential.

(3) Metabolic classification
3.1. Glucogenic amino acids
qAmino acids that gives glucose in
metabolism.
qThey are includes. glycine, alanine, serine,
cysteine, Isoleucine, aspartic acid, glutamic
acids, proline, Histidine, arginine, lysine and
methionine, Valine, threonine.
3.2. Ketogenic amino acids
qAmino acids that gives ketone bodies in
metabolism.
qThe only one : Leucine
3.3. Mixed amino acids
qAmino acids that gives both Ketone bodies
and glucose.
qThey are: Isoleucine , phenylalanine,
tyrosine, tryptophan, lysine.

General properties of amino acids:
(1) Physical properties
1. Solubility
qSoluble in water, strong acids and alkalis.
qInsoluble in alcohols or ether
2. Taste
qGlycine, Alanine, Serine, and Proline are sweet in taste.
q Tryptophan and Leucine are tasteless.
qArginine is bitter.
3. Optical activity All amino acids are optically active except Glycine.
4. Isomers Natural amino acid present in L-form
5. Amphoterism
They are amphoteric compounds due to presence of NH3 and
COOH groups.
What is zwitter ion/dipolar ion?! {point for research}
8/15/23 93

(2) Chemical Properties
1. Reaction of the amino group
(NH3)
q NH3 group reacts with acids to form salts.
qReaction with nitrous acid (Van slyke reaction).
qReaction with CO2 (Carbamino acid formation).
qFormaldehyde reacts with amino acids to form N-Methylene
amino acids (Sorensen formal titration).
qRemoval of amino group from the amino acids forming α-
keto acids (deamination reaction).
qMethylation of amino acids forming mono, di, trimethyl
derivatives.
2. Reactions of the acid
group(COOH)
qReacts with alkalis to form salts.
qReacts with alcohols to form esters.
qDecarboxylation (Formation of primary amines).
3. Reactions of both amino and
carboxyl groups
qNinhydrine reaction.
qPeptide bond formation
4. Reactions depending upon
presence of the radical (R).
qXanthoproteic reaction.
qMillon reaction.
qRosenheim reaction.
qSulpher reaction.
8/15/23 94

PEPTIDES
Structure:
(a) Peptide bond:
characters of peptide bond:
1) Rigid &planar bond with no free
rotation.
2) Present in trans form.
3) Non polar bond (non charged)
4) Have partial double bond
characters (shorter than single
bond).
5) Can form hydrogen bonds.
N- terminus
Peptide bond
C- terminus
Residue 1
Residue 2
Residue 3
Residue 4
Definition: Are compounds formed from less than 50 amino acid linked together by peptide
bonds. there are N& C terminus. Each amino acid in the chain is called residue.
(b) Peptide structure:

(c) Peptide bonds and peptide chains:
• Number of amino acids in the peptide chain =n e.g dipeptides, tripeptides,…
• Number of peptide bonds in the peptide chain = n-1
• If you have a peptide chain contains 40 amino acids how many peptide bonds
in this chain? # of peptide bonds = 40-1=39
• Position, number and type of amino acid in the chain determine the structure of
the peptide.
• Naming of peptide bonds: add yl to the end of amino acid for all amino acids in
the chain except the last one. E.g glutamyl-cyeteinyl-glycine
N-Gly-Glu-Ser-Ala-Gln-Met-C
N-Gly-Ser-Ala-Glu-Gln-Met-C
Peptide (a)
Peptide (b)

Biologically active peptides
Peptide Characters
(1) Glutathione Formed from 3 amino acids (glutamate-cysteine-glycine)
called ( γ-glutamyl-Cysteinyl-Glycine).
(2) Bradykinin •It is a nina peptides
•It is smooth muscle relaxant, vasodilator and
hypotension.
(3) B- Lipotropin Encephalin and Endorphins
(4) Hormones ACTH and glucagon & Posterior pituitary hormones like
Oxytocin and vasopressin
(5) Others as some antibiotics and antitumor and natriuretic factor

PROTEINS
Definitions and nature:
1)Proteins are compounds formed from amino acids linked together by peptide
bonds to form what is called peptide chain.
2)All 20 amino acids are sharing in the protein structure.
3)Some proteins formed from one peptide chain and others formed from many
chains.
4)The number of amino acids in chains should be more than 50 amino acids.
5) The protein molecular weight is measured by Daltons

Protein structure (conformation of proteins) Order
"levels" of Protein Structure (organization)
qThe twenty amino acids commonly found in proteins are joined together by peptide
bonds.
qThe linear sequence of the linked amino acids contains the information necessary to
generate a protein molecule with a unique three-dimensional shape.
q The complexity of protein structure is best analyzed by considering the molecule in terms
of four organizational levels, namely, primary, secondary, tertiary, and quaternary.
qAn examination of these hierarchies of increasing complexity has revealed that certain
structural elements are repeated in a wide variety of proteins, suggesting that there are
general “rules” regarding the ways in which proteins fold. These repeated structural
elements range from simple combinations of α-helices and β-sheets forming small motifs, to
the complex folding of polypeptide domains of multifunctional proteins.

I. Primary Structure of Proteins
1) The sequence of amino acids in a protein is called the primary
structure of the protein.
2) Genetic diseases result in proteins with abnormal amino
acids sequences.
3) Abnormal proteins with abnormal amino acid sequences are
usually non functional.
4) Peptide bond discussed before
Link of more than one amino acid
With peptide bond results in
Polypeptide chain.
NOTE
all amino acid residues have their
suffixes (-ine, -an, -ic, or -ate)
changed to -yl, with the exception
of the C-terminal amino acid.
e.g. a tripeptide composed of an
N-terminal valine, a glycine, and a
C-terminal leucine is called
valylglycylleucine.

II. Secondary Structure of Proteins
(A) α-Helix
α-Helix
Polypeptide chain
1
4
8
1
4
8

Bonds share in secondary structure
1) Peptide bond
2) Hydrogen bond
3) Ionic bond
4) Disulfide bond
5) Hydrophobic interactions

(B) ᵦ-pleated sheets
The chain arranged in sheets that may be
•Parallel to each other
•Anti-parallel to each others

III. Supersecondary structures (motifs)
1) Globular proteins are constructed by combining secondary structural elements
(α)helices, β)sheets, non repetitive sequences). These form primarily the core region—
that is, the interior of the molecule.
2) They are connected by loop regions (for example, β)bends) at the surface of the
protein.
3) Super secondary structures are usually produced by packing side chains from adjacent
secondary structural elements close to each other. Thus, for example, α)helices and
β)sheets that are adjacent in the amino acid sequence are also usually (but not always)
adjacent in the final, folded protein.
4) Proteins that bind to DNA contain one or more of a limited number of motifs.
5) The zinc finger motif is common, and is found in a number of proteins that function as
transcription factors

III. Tertiary Structure of Globular Proteins
1) The primary structure of a polypeptide chain
determines its tertiary structure.
2) “Tertiary” refers both to the folding of domains
(the basic units of structure and function).
3) The structure of globular proteins in aqueous
solution is compact, with a high density (close
packing) of the atoms in the core of the molecule.
Hydrophobic .
4) Side chains are buried in the interior, whereas
hydrophilic groups are generally found on the
surface of the molecule.
5) Domains are the fundamental functional and
three dimensional structural units of
polypeptides. Polypeptide chains that are greater
than 200 amino acids in length generally consist of
two or more domains.
6) The core of a domain is built from combinations of
supersecondary structural elements (motifs).
7) Folding of the peptide chain within a domain
usually occurs independently of folding in other
domains.
8) The four main bonds that are sharing in tertiary
structure are disulfide, hydrogen, hydrophobic,
and Ionic bonds

Point Motif Domain
Nature Chain like connection between the
secondary structure elements
Independent unit of 3D structure of protein
Level Super-Secondary Tertiary
Formation Formed from a connection between Alpha
helices and B-sheets through loops
Formed due to the interactions among amino
acids in the protein chain by disulfide,
hydrogen, electrostatic …. Bonds
Function Have structural function in the protein It perform the function of protein
Variability Have similar functions within protein
families
Have a unique function
Stability Not stable stable
Motif
Domain
Motifs and domains

IV. Quaternary structure of proteins
1) Many proteins consist of a single polypeptide chain, and are defined as monomeric proteins. However,
others may consist of two or more polypeptide chains that may be structurally identical or totally unrelated.
2) The arrangement of these polypeptide subunits is called the quaternary structure of the protein. Subunits
are held together by noncovalent interactions (for example, hydrogen bonds, ionic bonds, and hydrophobic
interactions).
3) Subunits may either function independently of each other, or may work cooperatively, as in hemoglobin, in
which the binding of oxygen to one subunit of the tetramer increases the affinity of the other subunits for
oxygen.
Hemoglobin (4 subunits)

Native
conformation
Biological
function
• Catalysis
• Protection
• Regulation
• Signal transduction
• Storage
• Structure
• Transport
Folding by
Chaperons
Can be fibrous or
globular
Unfolding
by
Denaturants
• Chemicals
• Physicals
• Biologicals
Loss of function
Loss of secondary and tertiary
structure
Some regain
Irreversible denaturation
Creutzfeldt-Jakob
disease
Alzheimer disease
Altered folding
Prion
Amyloid
Amino acids number and sequence
⍺- Helix
B-sheet
B-bends
Non repetitive structure
Suoer-secondary structure
Hydrogen bonds
Electrostatic interactions
Hydrophobic interactions
Disulfide bonds
Hierarchy of protein
structure
Primary
structure
Secondary
structure
Tertiary
structure
Quaternary
structure

Protein folding
1) Protein folding: is a physical process at which the protein take its final
3D structure shape.
2) Proteins during / after synthesis tended to take a stable shape
enables it to perform their functions (folding process).
3) Protein folding figure:
Protein Misfolding
1) Misfolded proteins are usually eaten by the cell through a process of protein degradation.
2) Deposits of these misfolded proteins are associated with a number of diseases including the amyloidosis,
allergies and neurodegenerative diseases.
Native protein
Folded protein
4) The folding process starts from N-terminal towards the C terminals
during protein synthesis (primary, secondary, tertiary then quaternary are
all the steps of protein folding).

Why most proteins when denatured do not resume their native conformations under favorable
environmental conditions?
One answer to this problem
1) the proteins start their folding just during their synthesis and this means that folding is a process
included in protein synthesis so missing of folding means missing of protein function.
2) In addition, a specialized group of proteins, named “chaperones,” are required for the proper
folding of many species of proteins.
3)The chaperones—also known as “heat shock” proteins—interact with the polypeptide at various
stages during the folding process.
4) The role of chaperons:
• Some chaperones are important in keeping the protein unfolded until its synthesis is finished.
• Some act as catalysts by increasing the rates of the final stages in the folding process.
• others protect protein during folding and synthesis process.
Role of chaperones in protein folding

Role of chaperones in protein folding

Denaturation of proteins
1) Protein denaturation results in the unfolding and disorganization of the protein's secondary and tertiary
structures, which are not accompanied by hydrolysis of peptides bonds.
2) Denaturing agents include
(a) Physical agents as heat, radiations and mechanical mixing,
(b) Chemical agents as organic solvents, strong acids or bases, detergents, and ions of heavy metals such as lead
and mercury and
(c) Biological agents as enzymes.
1) Denaturation may, under ideal conditions, be reversible, in which case the protein refolds into its original
native structure when the denaturing agent is removed. However, most proteins, once denatured, remain
permanently disordered.
2) Denatured proteins are often insoluble and, therefore, precipitate from solution.

CLASSIFICATION OF PROTEINS
Albumins and globulins
Basic proteins
qGlobins (Histones).
qProtamines.
Acidic proteins
qGladians
qGlutelins
Scleroproteins
qKeratins
qCollagen
qElastin
qReticulin
qPhosphoproteins
qLipoproteins
qGlycoproteins
qMetallproteins
qChromoproteins
qNucleoproteins
Primary derived
Denturated proteins
Secondary
derived
Hydrolytic proteins
Simple proteins Conjugated proteins Derived proteins
• Proteoses
• Peptones
• Peptides
• Proteans
• Metaproteins

(1) Albumin and globulins
Points Albumin Globulins
Solubility Water and salt solution Salt solution
Coagulation Heat Heat
Biological value High High
Essential amino
acids
Contains all essential amino
acids
Contains all essential amino acids
Digestion Easily digested Easily digested
Precipitation Full saturation with
ammonium sulphate
Half saturation with ammonium
sulphate
Molecular weight 68 KDa 150 KDa
Sources Egg albumin (Ovalbumin)
Serum albumin
Milk albumin (lactalbumin)
Egg globulins
Serum globulins
Milk globulins
Functions Keep blood osmosis
Transports elements,
hormones, vitamins
Transporation and main functions
as immunoglobulins (antibodies).
(A) Simple proteins

Points Globins Protamines
Solubility Water Ammonium hydroxide
Size 11-15 KDa Low size 49-50 amino acid long
4-5 KDA
Source Chromatin of all cells (abundant in
thymus and pancreas)
Sperm cells
Functions Chief component of chromatin Form complexes with nucleic acids
Amino acids Rich in histidine, lysine and arginine Rich in arginine
Lack tyrosine and tryptophan
Medical /biological
uses
• It responsible to the packaging of
DNA into smaller volume.
• Serve the control of gene
expression.
• Mixed with insulin to slow down the
duration of insulin action
• Protamine sulphate used as
antidote in heparin overdose
• Used in gene therapy
• Used to overcome obesity
• Used in cardiac surgery and
interventional radiology
(2) Basic proteins [Globins (histones) and Protamines]

Points Gladians Glutelins
Solubility Acids Dilute acids, bases, detergents
and reducing agents
Source Wheat and several cereals Wheat, rice grains
Types ⍺ , gamma and ⍵ 1. High molecular weight
glutelins
2. Low molecular weight
glutelins (similar to gladian)
Diseases Celiac disease: intolerance to
gluten in wheat
HMW glutelins are sensitizing
for celiac disease.
(3) Acidic proteins [Gladians and Glutelins]

Points Collagen Keratin Elastin Reticulin
Amino acid
contents
Rich in Proline/hydroxyproline and
glycine
Rich in Cysteine Rich in proline and lysine
but less hydroxyproline
and hydroxy lysine
Type III collagen
Peptide
chains
Helix of 3 chains Present in alpha helix or
beta sheets
700 amino acids 3 chains
Types Type I , II, III Alpha and beta synthesized
From precursor called
tropoelastin
Only one type
Site Connective tissue (ligaments and
tendons and part of dermis of skin)
Skin, hair, nails and claws lungs, the walls of large
arteries, and elastic
ligaments.
Liver, spleen and
kidneys
Commercial
uses
Surgical reconstruction Ceramics and cosmetics
industry
No commercial use No commercial use
Site of
formation
Fibroblast Keratinocytes connective tissue Reticular cells
Diseases
associated
1. Ehlers-Danlos syndrome (EDS)
due to defects in the fibrillar
collagen specially type III. There
are deficiency in enzymes [lysyl
hydroxylase or procollagen
peptidase ] or or from
mutations in the amino acid
sequences of collagen types I,
III, or V.
2. Osteogenesis imperfecta (OI): or
brittle bone syndrome due to
mutation in alpha 1 and 2 chains
of collagen.
1. Epidermolysis
Bulloosa simplex
(EBS).
2. Epidemolytic
hyperkeratosis (EH).
1. Marfan syndrome—a
connective tissue
disorder characterized
by impaired structural
integrity in the
skeleton, the eye, and
the cardiovascular
system.
2. Alpha -1 antitrypsin
deficiency: lung
problems
Reticulin fibrosis
(4) Scleroproteins (Fibrous proteins) albuminoids

(B) Conjugated proteins
Proteins Significance
(1) Phosphoproteins ü Proteins chemically bounded to phosphate groups (tyrosine, serine
and methionine) are target amino acids.
ü It plays a great role in the regulation of proteins
ü Most proteins are phosphorylated by kinases and dephosphorylated
by phosphatase.
ü Casein in milk and vitellin in egg yolk are forms of phosphoprotein.
(2) Metalloproteins Proteins conjugated with metals
• Iron-containing: ferritin, myoglobin, hemoglobin and
transferrin,hemosedrin, catalases, peroxidases, tryptophan
pyrrolase.
• Zinc-containing: insulin
• Copper-containing: ceruloplasmin, erythrocuprein, hepatocuprein,
cerebrocuprein and cytochrome oxidases.
(3) Chromoproteins Proteins conjugated with colored pigment.
• Red colored: as hemoglobin and cytochrome enzymes.
• Green proteins: contain magnesium as chlorophyll.
• Blue proteins: contain copper
• Yellow proteins: flavoproteins
• Brown to black: melanoproteins
(4) Nucleoproteins Protein conjugated with nucleic acids.
(5) Glycoproteins Discussed in carbohydrates chemistry chapter.
(6) Lipoproteins Discussed in lipids chemistry chapter.

(C) Derived proteins
Points Primary derived proteins Secondary derived proteins
Name Denturating proteins Hydrolytic proteins
Changes to protein Slight change in protein structure Marked or sever change in protein structure
and properties
Cause Denaturating agents Strong acids and alkalis and digestive
enzyme (proteases and peptidases)
Hydrolytic products No hydrolytic products or peptides There are cleavages and peptides
Primary structure It keeps its primary structure no cleavages Distorted primary structure
Members • Proteans: derived from globulins but
insoluble in salts e.g myosan from
myosin and fibrin from fibrinogen
• Metaproteins: coagulated proteins
• Proteoses: soluble in water but not
coagulated by heat
• Peptones: the same like proteoses but it
simpler and smaller than proteoses
• Peptides: small chain of amino acids
and also soluble in water but not
coagulated by heat.
• Proteoses->peptones->peptides->
amino acids
Primary derived protein Native protein
Proteose Peptone Peptide
Secondary derived protein

GENERAL PROPERTIES OF PROTEINS
1) Odor :odorless
2) Taste: tasteless
3) Solubility: neutral in water, acids or alkalies
4) Amphoterism: amphoteric substances.
5) Colloidal properties: they form colloids
1) Color reaction: gives (+) reactions with
specific amino acid.
2) Precipitation of proteins: proteins can
be precipitated by [Heat, salts of heavy
metals, alcohols, strong acids,
alkaloids, and radiation]
3) Proteins denaturation: physically,
chemically and biologically
denaturated.
8/15/23 120
Chemical
Physical

Items Peptides Proteins
# of amino acids Less 50 More 50
# of chains One One or more
Molecular weight Low High
Primary structure Present Present
Secondary structure - Present
Tertiary structure - Present
Quaternary structure - Present
Synthesis Through metabolic pathways Through translation
Breakdown By enzymatic digestion Denaturation
Heat coagulation Not coagulated Coagulated
Precipitation By full saturation By half saturation
Examples Bradikinins, glutathione, Oxytocin Insulin, enzymes, albumin
Proteins vs peptides

Enzymes
8/15/23 122
1. What enzyme means?
2. Aims of enzymes inside our cells
3. Difference between enzymes and other catalysts
4. general properties of enzymes.
5. Nature of enzymes
6. Difference between coenzyme and prothetic groups
7. How to measure enzyme activity
8. How to name enzymes
9. Enzymes classifications
10. Enzyme classes
Part 4

: En- zyme = in yeast
Inorganic catalysts
Enzymes
Point
Thermos table
Thermolabile
Effect of heat
Inorganic(acid, mineral, heat)
Organic
Nature
Non-protein compounds
Most enzymes are Proteins
Protein content
Non specific
Specific
Specificity
Low
High
Catalytic efficiency
Need high temperature and
pressure
Act at body temperature and pressure
Temperature and
pressure
8/15/23 123
ENZYMES
üEnzymes are biological catalysts which catalyze the chemical reactions in
all living cells.
üMost of them are proteins in nature.
üCan do their activity when they extracted from their original source!
What do enzymes mean?
What are the differences between enzymes and inorganic catalyst?

8/15/23 124
qAll enzymes are proteins (except ribosomes).
qEnzymes accelerate and increase the rate of the chemical reaction through
üKeep reaction equilibrium.
üNeeded by very small amount (nmol).
üNot consumed through their chemical reaction.
q They are highly specific for their substrates. Through their specific active site.
qThey lower the activation energy consumed during the reactions.
qEnzymes that possesses key reactions (committed steps) are regulatory in their
work.
qThey act at particular pH and temperature.
What are the general properties of enzymes?
Coenzyme
Active site
Substrate
Key-lock theory

8/15/23 125
Conjugated
(Holoenzyme)
Only proteins
e.g. Maltase, sucrase
Simple
ENZYME (Protein)
Protein part
(Apoenzyme)
Non Protein part
(cofactor)
Prosthetic group
Coenzyme
Enzyme
Enzyme
Coenzyme
Enzyme
Prosthetic group
Active site
Allosteric site

Organic
It called Coenzyme Mainly are minerals like
Cu, Fe, Mg, Mn
Tight bound to the enzyme
8/15/23 126
Cofactor
Inorganic
Can be separated from
enzyme after performing the
chemical reaction.
• Can not be separated from
enzyme after performing
the chemical reaction.
• It be added to it during its
synthesis.
It called prosthetic group
Like, FAD, Biotin
Loose bound to the enzyme
Like, NAD, NADP, Pyridoxal

Prosthetic groups
Coenzyme
Points
Inorganic or organic
Organic
Nature
Firmly attached to protein part
(apoenzyme)
Loosely attached to protein part
(apoenzyme)
Link to enzyme
Non dialyzable
(don’t leave enzyme)
Dialyzable
(can leave enzyme)
Dialysis
1. Metals: as copper, iron, zinc
2. Vitamins: as biotin attached
to carboxylases, or FMN
attached to
dehydrogenases.
Derived from a vitamin as FAD,
NAD, NADP, Pyridoxal
Members
8/15/23 127

Hydrogen carriers Non hydrogen carriers
NAD
NADP
FAD
FMN
Lipoic acid
CoQ
qCoA: acid carrier
qTTP: CO2 and Ketol carrier
qBiotin: CO2 carrier
qPyridoxal -P : Co2 carrier
qFolic acid: one carbon group carrier
qCobalamine: Methyl group carrier.
8/15/23 128
Enzyme-substrate complex
Product Enzyme
+
Enzyme substrate complex
Enzyme
Substrate

1. Trivial name: trypsin, pepsin,….etc
2. Attach (ase) to the end of substrate, e.g. maltase, sucrase, …etc
3. According to the type of the reaction, aminotransferases, decarboxylases, ….
4. IUB, substrate- Coenzyme-type of reaction, e.g. Lactate-NAD- oxidoreductase.
IUBMB, put code called Enzyme Commission Numerical Code (EC)
For more information you can visit https://enzyme.expasy.org
1st digit 2nd digit 3rd digit 4th digit
Class number
One – Six
Functional
group
upon
enzyme act
Coenzyme Substrate
Alcohol –NAD- Dehydrogenase EC= 1 1 1 1
8/15/23 129

8/15/23 130
Enzymes
classification
According
to the site
of action
Intracellular Extracellular
According
to enzyme
specificity
According
to function
Enzymes
classes
• Cytochrome oxidase
• Glucokinase
• Succinate dehydrogenase
• Glycogen synthase
• Glutamine synthetase
• Lipases
• Pancreatic amylases
• Pepsin
• Trypsin

8/15/23 131
Action
Members
Class
Add and remove hydrogen
Oxidases-Dehydrogenases
-Hydroperoxidases
(1) Oxidoreductases
Transfer functional groups
Transaminases –Kinases –
Translocases
(2) Transferases
Hydrolysis of substrate by adding
water
Esterases- Peptidases-
Phosphatases- Deamidases- Lipases-
Amidases
(3) Hydrolases
Splitting of substance with out
hydrolysis (addition or removal of
groups)
Decarboxylases-Carboxylase-
Carbonic anhydrase- Aldolase-
Enolase, etc.
(4) Lyases
Catalysis the conversion between a
compound isomers.
Racemases- Epimerases-
Isomerases- Mutases.
(5) Isomerases
Legate two chemical groups or
compounds.
glutamine synthetase and succinic
thiokinases
(6) Ligases
OTHLIL
For any info of enzymes you can visit : https://enzyme.expasy.org

Type Action Examples
(1) Absolute specificity The enzyme acts only on one
substrate
Urease, Uricase, Arginase.
(2) Relative specificity The enzyme acts on a group of
substances which are carrying
similar structures and similar bonds.
Lipases: triglycerides
Peptidases: peptides & proteins
(3) Group specificity The enzyme does not show
specificity to the bond only but also
to the group around the bond.
Aminopeptidase
Carboxypeptidase.
(4) Optical or stereo-
specificity
Enzyme acts on one isomer. Like
enzymes act on D&L sugars and
L&D amino acids.
L-amino acid oxidases
D-amino acids oxidases
(5) Dual specificity The enzyme can act on two
different substances e.g. xanthine
and hypoxanthine or glucose and
fructose
- Xanthine oxidase: can oxidize
hypoxanthine and xanthine to
uric acid.
Hexokinases: act on both
glucose and fructose or glactose

Enzyme
action
A. The energy
changes that occur
during the reaction
Energy barrier
separates reactants
from products
(Activation energy)
B. How the active
site chemically
facilitates catalysis
Role of the active
site

Progress of reaction
Free
energy
A
B
Initial state of
reactants
Final state
Products
-∆G
8/15/23 134
1. Free energy of activation: it is the energy consumed by substrates to become products
this called (-∆G).
2. Substrates do not changed to product directly it should be energized to reach
transition state firstly. At this state chemical bonds may breaks or formed to make a
product.
3. So what is the role of enzyme here: its role is to decrease the energy of activation
required by substrate to be a product.
Aà B
Transition state
(Uncatalyzed reaction)
Transition state
(Catalyzed reaction)
Initial state
Energy of activation
(Uncatalyzed reaction)
Energy of activation
(Catalyzed reaction)

(A) Key and lock theory
8/15/23 135
Substrate
Modifier
Allosteric site
Active site
(B) Induced fit theory (Hand-in-glove model)
Enzyme
Substrate
1the Active site not well-fitted at first
Substrate
2 binding of substrate will change the
active site shape
Substrate
3 now active site become fitted
with substrate
Enzyme
Enzyme Enzyme Enzyme

8/15/23 136
1. Enzyme concentration
2. Substrate concentration
3. Temperature
4. PH
5. Enzyme activators
6. Inhibitors

Certain substances may activate the enzymes
they include:
1. Metal ions:- e.g., chloride ions that activate
salivary amylase, Calcium ions that activates
blood clotting enzymes.
2. Enzymes:- some inactive enzymes need other
enzymes to activate it e.g.,
a. Auto activation: Pepsinogen to pepsin using
active pepsin.
b. Other enzymes: Enterokinase activates
trypsinogen to trypsin.
3. HCl: it starts the activation of pepsinogen to
pepsin.
4. Bile salts: activate pancreatic lipase.
8/15/23 137
Substance that decline the enzymatic activity
1. Reversible/ irreversible:
2. Competitive or noncompetitive
Reversible Irreversible
Binds noncovalent Bind permanently
Competitive or not Non competitive
Recovered Not recovered
Competitive Noncompetitive
Binds to active site Binds to other site
Recovered by increase
of S concentration
Recovered by increase
of I concentration
Both ES and EI
present
ES, EI and ESI can be
present

8/15/23 Aaser Illusterated Biochemistry AASER ABDELAZIM 138
Comparison among enzyme inhibitors
Items Competitive Non-competitive Uncompetitive
(anti-competitive)
Definition Inhibitor that compete
substrate to bind active site
Inhibitor binds enzyme in a site
rather than the active site
Inhibitor binds enzyme in a site
rather than the active site only
when ES is formed.
Binding site Active Allosteric Allosteric
Complexes EI or/and ES EI or ESI Only ESI
Reversibility Reversible Usually irreversible Irreversible
Shape Analogs to substrate Differ from substrate May analogs to substrate or
not
Recovering of inhibition By excess substrate No recovering No recovering (as substrate
increases the binding of
inhibitor to ES complexes
increases)
Km in presence of inhibitor
(enzyme affinity)
High Km /low affinity Unchanged/unchanged affinity Low Km/ high affinity
Vmax Unchanged
High substrate could arrive the
reaction to Vmax
Low
(enzyme could not perform the
reaction perfectly)
Low
(enzyme could not perform the
reaction perfectly)
Medical applications Therapeutic application
e.g.
1. Mevastatin inhibits HMG-
CoA synthase and lower
cholesterol synthesis
(hypolipidemic drug).
2. Allopurinol inhibits
xanthine oxidase and lower
uric acid formation
(hypouricemic drug)
Toxicological application
1. Lead inhibits Ferrochelatase
permanently and induce
anemia.
2. Arsenic inhibits
glycerldehyde-3-p
dehydrogenase.
3. Cyanide inhibits cytochrome
oxidase.
Therapeutic/ toxicological
1. Many anticancer agents
2. Amines inhibits
acetylcholinesterase.
3. Leucine and Phenylalanine
inhibit human alkaline
phosphatase (ALP).

Minerals
8/15/23 139
Part 5
1. Types of minerals
2. Metabolism of macro elements
3. Metabolism of microelements

Needed by amounts < 100 mg / day
Needed by amounts > 100 mg / day
Micro /trace elements
Macroelements
1. Iron
2. Copper
3. Zinc
4. Manganese
5. Selenium
6. Cobalt
7. Chromium
8. Molybdenum
9. Fluoride
10.Iodine
1. Calcium
2. Phosphorous
3. Chloride
4. Magnesium
5. Potassium
6. Sodium
15-8-2023 140
water and Mineral metabolism Dr / Aaser Abdelazim,
lecturer of Medical Biochemistry and Molecular Biology
Minerals
Macrominerals Microminerals

(A) Macrominerals

120 mg / 100 ml
Human milk only 30
mg /100 ml
800 mg / 100 gm 10 mg / 100 gm
20-25 mg / 100 gm
British add another
60 mg / 100 gm
800 mg /day
800-1200 mg / day
15-8-2023 142
(1) Calcium
(A) Sources
(B) Requirements

15-8-2023 143
(C) Functions of Calcium
Normal classification of
bone and teeth
Maintain cell membrane
permeability
Neuromuscular functions
1.Decrease Neuromuscular
excitability.
2.Regulate Muscle contraction.
3.Regulate transmission of nerve
impulses.
4.Cardiac conduction

15-8-2023 144
Blood clotting
• Ca+ ions play a main
role in intrinsic
pathway for blood
clotting
• Calcium is the main
activator for
prothrombin
Activator for enzymes
• Lipase
• Pyruvate kinase
• Succinate dehydrogenase
Second messenger for
hormones
Milk clotting
(C) Functions of Calcium
• Calcium
paracasienate

Blood stream
15-8-2023 145
(D) Calcium absorption
ü Calcium is absorbed by active transport mechanism form the upper part
of small intestines.
ü Usually blood Calcium is higher than Calcium level in intestines.
Intestinal lumen
Active vitamin D
CBP
Inactive vitamin D
PTH

Factors affecting calcium absorption
Factors promoting calcium absorption Factors inhibiting calcium absorption
Factor Action
High protein diets Amino acids forms
soluble slats with calcium
pH Acidic pH facilitate
calcium absorption
Lactate and citrate High dietary citrate and
lactate form soluble slats
with calcium
Factor Action
Abnormal fat
digestion
Fatty acids form insoluble
salts with calcium so it
inhibits its absorption.
Alkalinity Excessive alkalis decrease
or inhibits calcium
absorption.
Dietary phosphates,
phytates and
oxalates
Form insoluble salts with
calcium.

Other
tissues and
fluids
1%
skeleton
99%
Body calcium
1. In dynamics
2. Reservoir
3. Stabilizes blood calcium
Calcium phosphate
Calcium hydroxide
Hydroxyapatite
3
1
Bone / teeth
1200 gm
15-8-2023 147
(D) Body Calcium

15-8-2023 148
(a) Ionized calcium (50%)
o It is the physiologically active calcium.
o Its deficiency cause tetany.
(b) Non-ionized calcium (50%)
Diffusible (5%)
o Calcium forms
complexes with organic
acids
o As Calcium citrate
Non diffusible (45%)
o Bound mainly to albumin
o It form the transportable
form of calcium
o Its deficiency associated with
hypoproteinemia.
o Its deficiency does not cause
tetany.
(E) Blood Calcium
o Normal blood calcium level is 9-11 mg/dl with average (10 mg/dl).
o Calcium mainly concentrated in plasma and does not present in RBCs.
BLOOD CALCIUM

7 FACTORS AFFECTING BLOOD CALCIUM
Hormonal regulation of blood calcium
a
1. Parathyroid hormone PTH: increases blood calcium
2. Active vitamin D (Calcitriol): increases blood calcium
3. Calcitonin: decrease blood calcium
4. Katacalcin: decrease blood calcium
PTH
Calcitriol
Ca
Ca
Ca
1. katacalcin
+
+
+
Ca
15-8-2023 149

Calcitonin
katacalcin
Ca
+
Hypercalemia
Ca
-
Ca
+
Release
Deposition
Secretes
15-8-2023 150

Other factors regulating blood calcium
b
Ca/P ratio Blood PH Plasma proteins
Adult ratio
= 40
Infant ratio
= 50
Ca only
ionized at
PH=7.4
Alkalosis
inhibits Ca
ionization
Protein deficiency
decreases the non
diffusible Ca level
15-8-2023 151

8 CALCIUM EXCERTION
Ca
56-75% of excreted Ca
Food Ca
Body Ca
Blood Ca
25-35% of excreted Ca
50-250 mg / day
15-8-2023 152

(F) Alterations in blood calcium
Hypercalcemia Hypocalcemia
Primary Parahyperthyroidism:
• usually due to adenomas in parathyroid
glands.
• Calcium levels may reach 20 mg/dl.
Hypoparathyroidism: low PTH
Ectopic cells in many malignancies:
which lead to increase PTH.
Alkalosis:
decrease calcium absorption
Excess intake of vitamin D or calcium or both
in cases of self medications
Kidney diseases:
Loss of vitamin D activation
Milk-alkali syndrome:
high doses of milk for long periods.
Lead to high calcium absorption.
As milk used to treat peptic ulcers.
The effect of hypocalcemia
a) Acute deficiency: tetany and carpopedal spasm
b) Chronis deficiency: induces rickets in children
and osteomalcia in adults.
Bone diseases: as in bone malignancies,
multiple myeloma, Paget's disease.
Drugs: thiazides diuretics
Other causes:
Thyrotoxicosis, Cushing syndrome

15-8-2023 154
water and Mineral metabolism Dr / Aaser Abdelazim, lecturer of Medical Biochemistry and Molecular Biology
(2) Phosphorus
i) Sources
ii) Absorption
• Phosphorus is absorbed form mid jejunum.
• Absorption is controlled by active vitamin D.
• Factors affecting Calcium absorption are the same affect the Phosphorus absorption.
iii) Body phosphorus
• Total body P is about 800 g.
• 80% in skeleton in a form of hydroxyapatite.
• 20% in other tissues mainly intracellularly and other body fluids.
Required by 800 mg/day for adults

iv) Blood phosphorus
• Normal plasma P is about 3-5 mg/dl.
• Other forms are phospholipids and organic phosphates like ATP and G-6-P.
v) Factors affecting blood phosphorus
Blood
Parathyroid (PTH) Calcitriol
+
Kidneys
Intestines
Bones
+
Urinary excretion
-
Low blood phosphorus
I
n
c
r
e
a
s
e
r
e
s
o
r
p
t
i
o
n
Increase resorption
Increase
m
obilization
90% of
excreted P is
through urine

vi) Functions of phosphorus
Function Significance
Skeleton structure Enters in the bones and teeth in the form of hydroxyapatite
Blood buffers Phosphate buffer system in urinary system
Cellular components Ø Nucleic acids
Ø Phospholipids
Ø Phosphoproteins
Ø Coenzymes as NAD and NADP
Ø High energy compounds as ATP, GTP, creatine –p and arginine-p.
Ø Messengers like cAMP and cGMP.
Ø Carbohydrates intermediates as G-6-P and F-1-P.
vii) Abnormalities of serum phosphorus
Hyperphosphatemia Hypophosphatemia
Hypoparathyroidism: low PTH production Hyperparathyroidism: high PTH production
Acidosis Excessive use of antacids
Hypervitaminosis D Vitamin D deficiency
RBCs hemolysis Renal tubular diseases (renal failure)
Chronic alcoholism

(3) Magnesium
i) Sources:
• all leafy vegetables containing chlorophyll.
• Adults required 400 mg/day
ii) Absorption: upper part of small intestine.
Excretion: through feces.
iV) Blood magnesium:
• Plasma Mg = 2-3 mg/dl
• Mainly present inside RBCs it is 3 times greater than plasma.
iii) Body magnesium:
• 70 % in bones and teeth
• 30% other tissues
Skeleton structure Enters in the bones and teeth in the form of hydroxyapatite
Enzyme activation Kinases activation
Active transport Ø It is required for active transportation of [Ca, Na, K].
Muscles and nerves Ø Important for muscles contraction
Ø Decrease the neuromuscular excitability.
V) Functions of magnesium

(4) Sodium
i) Sources:
• Table salt is the main source.
• Aldus need 5 g/day.
ii) Absorption:
Completely absorbed form ileum
iii) Body sodium:
1/3 in skeleton
2/3 in other tissues it’s the main extracellular cation
iv) Blood sodium:
137-143 mmol/L
It could be affected by
1. Aldosterone and rennin angiotensin system: reabsorp Na
2. GFR and renal blood flow
3. ANF: eliminates Na form blood

vi) Functions of sodium
Osmotic blood pressure Maintain the osmotic pressure and blood volume
Impulses Help in the transmission of nerve impulses.
Contraction of muscles
Enzymes Ø Na/K ATPase
Acid base balance Ø Regulation
vii) Abnormalities of serum sodium
Hypernatremia Hyponatremia
Cushing syndrome: high glucocorticoids Addison disease: low aldosterone
Conns disease: high aldosterone Renal failure: low renal absorption of Na.
Diabetes insipidus: loss of water Hypotonic dehydration: loss of both water and Na.
Drugs: ACTH and cortisones Use of diuretics: thiazides
Sodium toxicity can induce severe hypertension in susceptible persons

(5) Potassium
ii) Absorption:
• Small intestines
i) Sources:
• Vegetables, fruits (banana) and nuts.
• Required by 4 g/day
iii) Body potassium:
• 2/3 in body and tissue fluids (main intracellular cation in the body).
• 1/3 in skeleton
iv) Blood potassium:
• 3.5-5 mmol/L
v) Functions of potassium:
Osmotic blood pressure Maintain the osmotic pressure and blood volume
Impulses Help in the transmission of nerve impulses.
Contraction of muscles
Enzymes Ø Na/K ATPase
Acid base balance Ø Regulation

vi) Alterations in blood potassium:
Hyperkalemia Hypokalemia
Addison disease: low aldosterone Alkalosis: shifting of K to cells due to low H
Acidosis: shifting of K outside cells to blood. Treatment of hyperglycemia: with out giving K
Tissue necrosis: in burns due to leakage of K
from cells to blood.
Excessive vomiting and diarrhea: loss more K
Acute and chronic renal failure: due to
oliguria (retention of potassium).
Cushing syndrome: high glucocorticoids
Uncontrolled diabetes mellitus: lack of
insulin interfere with trapping of potassium
Primary and secondary aldosteronism
High use of diuretics: loss of K
N.B acute hyperkalemia:
if the blood potassium reach > 6.5 mmol/L it can lead to cardiac arrhythmias
and even cardiac arrest.

(6) Chloride
ii) Absorption:
• Small intestines
• Excreted in urine
i) Sources:
• Table salt is the main source
• Required by 5g/day for adult
iv) Blood chloride:
• 96-106 mmol/L
v) Functions of chloride:
Extracellular anion Main extracellular anion
Osmotic pressure Maintain blood osmotic pressure with sodium and regulate fluid
volume.
Gastric HCl Ø Essential for formation of gastric HCl
Enzymes activation Ø Activates salivary and pancreatic amaylases

vi) Alterations in blood chloride:
Hyperchloremia Hypochloremia
Hyperchloremic acidosis:
Loss of HCO3 in exchange with Cl lead to
increase blood Cl levels this occurs in:
1. Renal tubular acidosis
2. Hyperventilation
Hypochloremic alkalosis:
Decrease blood Cl due to loss in exchange of HCO3
leading to alkalosis this can occur in intestinal
obstruction leading to excessive vomiting.
Glomerulonephritis: loss of HCO3 in
exchange with Cl
Addison disease: low aldosterone leading to loss of
Na with Cl
Eclampsia: toxicity of pregnancy Diabetes insipidus: loss of water with electrolytes
and chloride

(B) Microminerals
Trace elements

Liver Heart kidneys Spleen Fish Molasses
Dates Egg yolk Spinach consider a poor source!
15-8-2023 165
(1) Iron
(a) Sources of iron
Requirement
• Adult need 10 mg/day
• Pregnant and lactating women need 30 mg/day

IRON METABOLISM
Total body iron = 45 mg/kg Main constituent of
hemoglobin
Enter in cytochrome
structure and respiratory
chain enzymes
Transports oxygen
between tissues
Cellular respiration
and oxidation
processes
15-8-2023 166
(b) Functions of iron and iron metabolism
Hemoglobin Main component of hemoglobin
Myoglobin Store oxygen in skeletal and cardiac muscles
Respiratory enzymes Ø For the transfer of H and utilization of O2 for energy production
Cytochrome P450 Ø Detoxify drugs

Duodenum
Site of absorption
Proximal part of Jejunum
Diet contains 10-20 mg iron
/day
10-20 % of diet
absorbed /day
15-8-2023 167
(c) Absorption of iron

Mechanism of iron absorption
Mucosal block theory
Mucosal cells Blood
Intestine lumen
Fe++ Fe++
Fe+++ Apoferritin
Ferritin Fe++
Non absorbed
iron (80-90%)
Excretion
Depends on body need
Its amount is limited
when it get
saturated iron
absorption is
blocked
15-8-2023 168
a

Mucosal cells
15-8-2023 169
Recent theory for Iron Absorption
b
Fe++
Iron receptors
Iron carrier protein
Fe++
Ferritin
Fe++
Fe++
Fe++
As a storage not as a carrier
Blood
Ferroxidase

Points Mucosal block theory Recent theory
Iron receptors No receptors for iron There are iron receptors on
mucosal cells
Absorption
state of iron
Ferrous state Ferrous state
Iron carrier
protein (ICP)
Not present Present, is responsible for iron
uptake
Ferroxidase Present and converts ferrous
to ferric
Not present
Ferric ions Formed inside mucosal cells Not formed iron always in ferrous
state
Apoferritin Present and joined to ferric
ions to be ferritin
Not present
Ferritin Act as an iron carrier Act as an iron storage
Theories for iron absorption

FACTORS AFFECTING IRON ABSORPTION
3
Cooking of
food and
gasteric
HCl
Reducing
substances
Body need
Iron
liberation
from organic
compounds
Fe++
Fe+++
Diets high
in
Phosphates
and
phaytates
Steatorrhea
(fat form
isoulble
saop with
iron)
Alkalies (tea)
Insoluble salt with iron
Ferrous into ferric
15-8-2023
171

15-8-2023 172
RBCs
iron
66%
Tissue
iron
33%
Plasma
iron
1%
Body iron
3-5 grams
Hemoglobin
(d) Body iron

15-8-2023 173
Tissue iron
Available form (29%) Non available form (4%)
Ferritin Hemosiderin
Myoglobin
Respiratory cytochromes
Catalase and peroxidases
Tryptophane oxygenase
Cytochrome P 450
1. Carry 24 atoms of
iron
2. Present in iron
stores
• Liver
• Spleen
• Bone marrow
• Intestine
Iron store : LIBS
Granules
composed of
iron +proteins+
polysaccharides

15-8-2023 174
Plasma iron
Transferrin
Fe+++
Fe+++
180-450 µg/dl
60 - 160 µg/dl
100%TIBC
Fe+++
Fe+++
60-160 µg/dl
30%TIBC
TIBC: Is the maximum amount
of iron attached to transferrin =
(180-450 µg/dl)
Ferritin
Very low concentration in plasma
Iron body store
Plasma Ferritin Plasma Ferritin
1. Iron overload
2. Cancer
3. Liver diseases
Iron depletion
Iron deficiency anemia

(e) Transportation and storage of iron
Fe+2
Fe+2 Fe+3
Transferrin
Ceruloplasmin
Kidneys
Bone marrow
Intestines
Hemoglobin synthesis
Iron not excreted in urine
Iron excreted in feces
Other excretory pathways
1. Menstruation and
pregnancy in females
2. Desquamated skin and
intestinal mucosa

(f) Alterations in blood iron
Iron overload Iron deficiency anemia
Causes:
1. Repeated blood transfusion with out care
2. Intravenous load of iron with out
monitoring
3. Hemochromatosis: (hemosiderosis/
bronze diabetes)
Hereditary disorders at which iron abnormally
absorbed with high amount over the need of
human body
Iron is deposited in a form of hemosiderin in
Liver: causing cirrhosis
Pancreas: causing fibrosis and lead to diabetes
mellitus
Skin: causing bronze discoloration of skin
Causes:
1. Deficient iron intake
2. Impaired iron absorption: steatorrhea or
abdominal and intestinal surgery
3. Excess iron loss: menstrual loss, GIT bleeding in
case of some parasites.
4. Excess bleeding in severe wounds.
Biochemical changes and picture:
1. Plasma iron: increased
2. TIBC: decreased
3. Ferritin: increased
Biochemical picture:
1. Plasma iron: decreased
2. TIBC: increased
3. Ferritin: decreased
4. CBC: blood cells become hypochromic microcytic
cells.

15-8-2023 177
Iron deficiency anemia Liver disease Iron overload
Plasma iron
Transferrin
TIBC
Plasma iron
Transferrin
TIBC TIBC
Transferrin
Plasma iron
Alterations in plasma iron

(2) Copper
(a) Sources of copper
Liver, kidneys, dried legumes and nuts
(b) Absorption
Upper small intestine
(c) Body copper
Ø 100 -150 mg present in the body
Ø 64 mg (50%) in muscles alone.
Ø The remain part distributed in other tissues like livers and kidneys.
(d) Blood copper
Blood copper Significance
In plasma (90ug/dl)
a) Ceruloplasmin (90%) • Copper binding protein each molecule can bind to 6 atoms of Cu
• It acts as ferroxidase enzyme during iron metabolism.
b) Albumin (10%) It acts as carrier for copper in blood
In red blood cells (100ug/dl )
In associated with superoxide dismutase (erythrocuprein)

(e) Functions copper
It is essential for: 1. Hemoglobin synthesis
2. Bone formation
3. Maintenance of myelin of nerves
It is constituent of: 1. Ceruloplasmin
2. Superoxide dismutase
3. Cytochrome oxidase
It activates: 1. Tyrosinase
2. Uricase
3. Dopamine hydroxylase
(f) Requirements and excretion
Ø Adult person requires 2-3 mg /day.
Ø It excreted mainly in bile.
Ø Other way of excretion is urine (but it is minimal due high MW of cerulplasmin)

(g) Alterations of blood copper
Hypercupremia Hypocupremia
Causes:
1. Mainly due to infections
2. Inflammatory conditions
3. Malignancy conditions
which lead to increase plasma ceruloplasmin
as (acute phase protein).
Causes:
1. Anemia (hypochromic microcytic anemia)
2. Impaired bone mineralization.
3. Wilson disease: accumulation of large amount of
copper in:
o Liver: causing cirrhosis
o Lenticular nucleus of brain: causing abnormal
movement
o Cornea: causing greenish-brown discoloration of
the corneal margin which called Kayser-Fleisher
rings.
o Kidneys: causing tubular damage.
Wilson disease may results form:
1. Excess cupper absorption from intestines
2. Retention of cupper in bile

(3) Zinc
(a) Sources of Zinc
Meat, liver, eggs, seafood, milk, grains
(b) Absorption
Upper small intestine mainly (duodenum)
(c) Body Zinc
Ø 2 g present in the body
Ø 20% is present in skin alone.
Ø The remain part distributed in other tissues like bone, teeth, spermatozoa,
prostate, epididymis and pancreas.
(d) Blood Zinc
Ø 70-150 ug/dl
(e) Zinc requirements and excretion
Ø Adults need 10-20 mg/day
Ø Mainly in feces.

(f) Functions Zinc
It is essential for: 1. Growth and reproduction
2. Tissue repair and wound healing
3. Vitamin A metabolism (mobilization and disterbuation)
It is constituent of: 1. Alkaline phosphatase
2. Carbonic anhydrase
3. Superoxide dismutase
4. Carboxypeptidase
5. RNA polymerase
It form a complex with: 1. Insulin helping in its (crystallization, storage and release)
(g) Zinc deficiency may lead to:
Ø Hypogonadism
Ø Poor healing of wounds
Ø Poor appetite and retarded growth in child
Ø liver cirrhosis
Ø Diarrhea
Ø Dermatitis
Ø Confusion, apathy and depression

(4) Iodine
(a) Sources of Iodine
• Table salt
• Fish, seafood, weeds, vegetables grown near seaboards
(b) Absorption
Small intestines
(c) Body iodine
Ø 25-50mg present in
Ø Thyroid gland (50%) as thyroglobulin.
Ø Thyroid hormones
(d) Blood iodine
Ø Organic iodine (4-8 ug/dl)
Ø Inorganic iodine (1-2 ug/dl)
(e) Iodine requirements and excretion
Ø Adults need 100 -150 ug/day
Ø Mainly in urine.

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