Carbohydrates ppt Starch cellulose Biochemistry

1. Carbohydrates
 Polyhydroxy compounds (poly-alcohols) that contain a
carbonyl (C=O) group
 Elemental composition Cx(H2O)y
 About 80% of human caloric intake
 >90% dry matter of plants
 Functional properties
– Sweetness
– Chemical reactivity
– Polymer functionality

2. Types of Carbohydrates

3. Monosaccharides
 Monosaccharides are categorized by the number of
carbons (typically 3-8) and whether an aldehyde or ketone
 Most abundant monosaccharides are hexoses (6 carbons)
 Most monosaccharides are aldehydes, i.e. aldoses
O
H
C
H C OH
H
H C OH
C O
aldehyde ketone

4. Fisher projections
H C OH
H
H
H
O
H C 4 OH
5
6 C H2OH
C1
C2 OH
HO C3
H
O
H
C H2OH
1
C
2
HO C
3
H C OH
4
C OH
5
6C H2OH
D-fructose
(an ketohexose)
D-glucose
(an aldohexose)

7. Cyclic Forms
O
OH
HO
OH
HO
H
 Lowest energy state
H
C1
H
2C
4
C
6
CH2OH
C5
H
C3
H
-D-glucopyranose (glucose)
—an aldose
a hexose
an aldohexose
—C1 chairconformation
-D-fructopyranose (fructose)
—a ketose
a hexulose
a ketohexose
—1C chair conformation
O
C
H
H
OH
OH
H
OH
CH2OH
1
2C
C3
H
C
OH 4
5
6C
H

8. Ring Nomenclature
 pyranose is a six-membered ring (a very stable
form due to optimal bond angles)
 furanose is a five-membered ring

9. Chirality
 Geometric property of a rigid object (or spatial
arrangement of atoms) of being non-super-imposable
on its mirror image
H
H C OH
HO C H
H C OH
its mirror image
is an "optical
isomer"
C OH
CH2OH
H C
O 4 chiral centeres.g. atC2 carbon: This
structure has a non-
superimposable mirror image
CHO
(CHOH)3CH2OH
H
C2
OH

10. Isomers
 Isomers are molecules that have the same
chemical formula but different structures
 Stereoisomer differs in the 3-D orientation of atoms
 Diastereomers are isomers with > 1 chiral center.
– Pairs of isomers that have opposite configurations at one
or more of the chiral centers but that are not mirror images
of each other.
 Epimers are a special type of diastereomer.
– Stereoisomers with more than one chiral center which differ in
chirality at only one chiral center.
– A chemical reaction which causes a change in chirality at one
one of many chiral center is called an epimerisation.

11. Enantiomers
 Isomerism in which two isomers are mirror
images of each other. (D vs L)

13. Anomer
 An anomer is one of a special pair of
diastereomeric aldoses or ketoses
– differ only in configuration about the carbonyl carbon
(C1 for aldoses and C2 for ketoses)

14. Carbonyl Group
 Carbonyl groups subject to nucleophilic attack,
since carbonyl carbon is electron deficient:
– -OH groups on the same molecule act as
nucleophile, add to carbonyl carbon to recreate ring
form

15. OH
H
O
O
H
O
H
O
H
OH
O
O
5
5
5
5 1
1
1
1
 anomer  anomer
Carbonyl carbon freely rotates
 O can attack eitherside

16. Specification of Conformation, chirality
and anomeric form of sugars
 Determination of chair conformation
– Locate the anomeric carbon atom and determine if numbering
sequence is clockwise (n= +ve) or counterclockwise (n= -ve).
– Observe if the puckered ring oxygen atom lies “above” (p= +ve)
the plane of the ring or below (p= -ve).
– Multiply n*p. If the product is +ve then C1, -ve then 1C
 Determination of chiral family
– Locate the reference carbon atom contained within the ring and
determine whether the bulky substituent (OH or CH2OH) is
equatorial (r= +ve) or axial (r= -ve).
– Multiply n*p*r. If product is +ve the chiral family is D, when it is
–ve the chiral family is L

17.  Determination of Anomeric form:
– Determine if the hydroxyl substituent on the anomeric carbon atom is
equatorial (a= +ve) or axial (a= -ve).
– Multi[ly (n*p) by (n*p*r) by a. When the product is positive, the anomer
is ; when the product is negative the anomer is 
Specification of Conformation, chirality
and anomeric form of sugars

18. Mutarotation
 The - and - anomers of carbohydrates are typically stable solids.
 In solution, a single molecule can interchange between
– straight and ring form
– different ring sizes
– α and β anomeric isomers
 Process is
– dynamic equilibrium
– due to reversibility of reaction
 All isomers can potentially exist in solution
– energy/stability of different forms vary

19. Mutarotation : interconversion of -
and - anomers
 For example, in aqueous solution, glucose exists as a
mixture of 36%  - and 64%  - (>99% of the pyranose
forms exist in solution).

20. Anomer Interconverision
80
70
60
50
40
30
20
10
0
%
of
all
isomers
D-glucose D-fructose D-mannose D-galactose
α-pyranose
β-pyranose
α -furanose
β-furanose
Generally only a few isomers predominate

21. +57.2o
+112o
+19o
pure -D-(+)-glucopyranose1
[D
66% 
34% 
pure -D-(+)-glucopyranose2
TIME(min)

23. OH
HO OH
O
O
HO
OH
OH
O
HO
OH OH
OH
H
C
OH
OH
H
OH
HO OH
O
OH
OH
OH
OH
OH
H
CH2OH
HO OH
O H
Mutarotation of ribose
hydrate (0.09%) H
H
H OH
CH2OH
keto-form (0.04%)
-pyranose (20.2%)
-furanose (7.4%)
HO
-pyranose (59.1%) -furanose (13.2%)

24. Stability of
Hemiacetals/Hemiketals
 As general rule the most stable ring
conformation is that in which all or most of
the bulky groups are equatorial to the axis of
the ring

25. Reactions
 Isomerization
glucose
 Oxidation
R-CHO
R-CH2OH
fructose mannose
R-COOH
R-COOH
 Reduction
sugar sugar alcohols
 Acetal formation
sugar glycoside
 Browning reactions
O
H C
H C OH
HO C H
H C OH
H C OH
CH2OH
carbonyl group is key

26. Isomerization
 Isomerization is possible because of the
“acidity” of the  hydrogen
O
H C OH
H C OH
CH2OH
 hydrogen H C
H C OH
(on C next
to carbonyl)HO C H
O O
H C
C OH
HO C H
H C OH
H C OH
CH2OH
keto form
base
H C
C OH
HO C H
H C OH
H C OH
CH2OH
enol form

27. Isomerization
O
2
C H OH
H C
H C OH
HO C H
H C OH
H C OH
O
2
C H OH
H
HO C H
H C OH
H C OH
H C
HO C C O
CH2OH
HO C H
H C OH
H C OH
CH2OH
D-fructose
D-glucose D-mannose

28. Oxidation/Reduction
Oxidation
Increase oxygen or decrease hydrogen
Increase oxidation state
Remove electrons
Reduction
Decrease oxygen or increase hydrogen
Decrease oxidation state
Add electrons

29. Oxidation
 Carbonyl group can be oxidized to form
carboxylic acid
 Forms “-onic acid” (e.g. gluconic acid)
 Can not form hemiacetal
 Very hydrophillic
– Ca gluconate
 Can react to form intramolecular esters:
– lactones

30. Oxidation
 Also possible to oxidize alcohols to carboxylic
acids
– “-uronic acids”
 Galacturonic acids
 Pectin
 Reactivity
– Aldehydes are more reactive than ketones
 In presence of base ketones will isomerize
 Allows ketones to oxidize

31. Reducing sugars
 Reducing sugars are carbohydrates that can
reduce oxidizing agents
 Sugars which form open chain structures
with free carbonyl group
 Reduction of metal ions
– Fehling test: CuSO4 in alkaline solution

32. Reduction
 Carbonyl group can be reduced to form alcohol
– hydrogenation reaction
 Forms sugar alcohol (“-itol”)
– glucose
– mannose
– xylose
glucitol (aka sorbitol)
mannitol
xylitol
 Sweet, same calories as sugar, non-cariogenic
 Very hydrophillic
 Good humectants

34. Stability of acetals
 Pyranose >>>> Furanose
 β -glycosidic > α-glycosidic
 1,6>1,4>1,3>1,2
 Allow to predict stability of glycosidic linkages
in terms of their resistance to hydrolysis
– Gentiobiose

35. Acid catalyzed Rxns
 Acid hydrolysis of hemiactals and hemiketals
(mutarotation)
 Anhydro sugars
– 1C conformation
 Reversion sugars
– Formation of oligosaccharides under conditions of high sugar
concentration, dilute acid……. Maple syrup, fruit juice
concentrates
– Detection of invert sugar in juices/honey
 Enolization and Dehydration
– Formation of 3-deoxyosones and HMF/furfural

36.  Hydrolysis of hemiactals and hemiketals
(mutarotation)
– Base catalyzed loss of H from anomeric –OH
 Acetals and Ketals are stable
– Sugar esters will be hydrolyzed in alkali
 Enolization
– Favored by alkali
 Reduction of metal ions
– Alkali prevents hydrolysis of non-reducing sugar
Base catalyzed Rxns

38. Introductory Biochemistry

39. What is Biochemistry?
• Biochemistry = chemistry of life.
• Biochemists use physical and
chemical principles to explain
biology at the molecular level.
• Basic principles of biochemistry are
common to all living organism

40. How does biochemistry
impact you?
• Medicine
• Agriculture
• Industrial applications
• Environmental applications

41. Principle Areas of
Biochemistry
• Structure and function of biological
macromolecules
• Metabolism – anabolic and catabolic
processes.
• Molecular Genetics – How life is
replicated. Regulation of protein
synthesis

42. Once upon a time, a long long time ago…..
Vitalism: idea that substances and processes
associated with living organisms did not
behave according to the known laws of
physics and chemistry
Evidence:
1) Only living things have a high degree of
complexity
2) Only living things extract, transform and
utilize energy from their environment
3) Only living things are capable of self
assembly and self replication

43. Origins of Biochemistry:
A challenge to “Vitalism.”
Famous Dead Biochemist!

44. Fallacy #1: Biochemicals can only be
produced by living organisms
•Dead Biochemist #1
•1828 Friedrich Wohler

45. Fallacy #2: Complex bioconversion of
chemical substances require living matter
Dead Biochemists #2
•1897 Eduard Buchner
Glucose + Dead Yeast = Alcohol

46. Dead Biochemists #3
• Emil Fischer
Fallacy #2: Complex bioconversion of chemical substances require living
matter

47. Fallacy #2: Complex bioconversion of chemical substances require living
matter
Dead Biochemists #4
1926 J.B. Sumner

48. Findings of other famous dead biochemist
• 1944 Avery, MacLeod and McCarty identified
DNA as information molecules
• 1953 Watson (still alive) and Crick proposed the
structure of DNA
• 1958 Crick proposed the central dogma of
biology

49. Organization of Life
• elements
• simple organic compounds (monomers)
• macromolecules (polymers)
• supramolecular structures
• organelles
• cells
• tissues
• organisms

50. Range of the
sizes of objects
studies by
Biochemist and
Biologist
1 angstrom = 0.1 nm

51. Most abundant, essential for all organisms: C, N, O, P, S, H
Less abundant, essential for all organisms : Na, Mg, K, Ca, Cl
Trace levels, essential for all organism: Mn, Fe, Co, Cu, Zn
Trace levels, essential for some organisms: V, Cr, Mo, B, Al, Ga, Sn, Si,
As, Se, I,
Elements of Life

52. Important compounds, functional groups

53. Many Important Biomolecules are Polymers
protein complex
protein subunit
amino acid
membrane
phospholipid
fatty acid
cellw
all
cellulose
glucose
c
hromos
ome
DNA
monomer
polymer
supramolecular
structure
lipids proteins carbo nucleic acids
nuc
leotide

54. Lipids
membrane
phospholipid
fatty acid
monomer
polymer
supramolecular
structure

55. Proteins
monomer
polymer
supramolecular
structure
amino acid
protein subunit
Enzyme complex

56. Carbohydrates
cellw
all
cellulose
glucose
monomer
polymer
supramolecular
structure

57. chromatin
DNA
nucleotide
monomer
polymer
supramolecular
structure
Nucleic Acids

58. Common theme:
Monomers form
polymers through
condensations
Polymers are broken
down through
hydrolysis.

60. Prokaryote Cell

61. Cellular Organization
of an E. coli Cell
200 – 300 mg protein / mL cytoplasm

62. Eukaryote Cell