Main simple and complex proteins along with their classification are presented. Simple proteins main features. Gluten disease. Nucleic acids. Chromatine. Participation in transcription and replication. Detailed explanation of DNA and RNA structure
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Simple and complex protein. s2021 (2)
1. SIMPLE AND COMPLEX PROTEINS.
HEMOGLOBIN, its heterogenity and cooperativeness.
GLYCOPROTEINS: IMMUNOGLOBULINS.
METALO PROTEINS.
LIPOPROTEINS.
In The Name of Allah, The Most Merciful, The Most
Compassionate
Mahira Amirova
Associate Professor
Biochemistry Department
Azerbaijan Medical University
Year 2021
2. CLASSIFICATION OF PROTEINS
DEPENDING ON THEIR CONTENT
• All proteins sort into simple and complex.
Simple proteins consist of amino acids only,
while complex proteins have an additional
non-protein moiety.
• Complex proteins are: nucleoproteins,
phosphoproteins, chromoproteins (with color
pigment), glycoproteins, lipoproteins and
metalloproteins.
4. Depending on their solubility, simple proteins are
classified into following classes:
o proteinoids, or scleroproteins,
o albumins and globulins,
o prolamins and glutelins,
o protamines and histones
5. Scleroproteins are not dissolved in water and any
saline solution.
Albumines and globulins are separated with
salting out. Globulins are precipitated with a half-
saturated ammonium sulfate solution, while
albumins - with saturated ammonium sulfate .
This method of separation is called salting out.
Prolamins and glutelins are dissolved in 70-80%
ethyl alcohol. They are rich in proline and
glutamic acid.
Protamines and histones are alkaline proteins
6. Scleroproteins (proteinoids) or fibrous
proteins
Connective tissue: extracellular matrix, skin, cartilage, ligaments,
tendons, blood vessel walls, and the sclera and cornea of the eye,
basement membranes are rich in collagen and elastin . In some
tissues (the kidney and the lung) they act as semipermeable filtration
barrier to macromolecules in organs (especially basement membrane
of kidney).
Collagen contains hydroxyproline and hydroxylysine, which
are not present in most other proteins. Hydroxyproline maximizes
formation of inter-chain hydrogen bonds that stabilize the triple-
helical structure. The hydroxyl group of the hydroxylysine residues of
collagen is often glycosylated. Most commonly, glucose and galactose
are sequentially attached to the polypeptide chain prior to triple-helix
formation.
Collagen and elastin aссumulate in inflammation leading to scarring
(in the liver may result in cirrhosis)
7. Major proteins of connective tissue: collagen
and elastin, that are synthesized in fibroblasts
Unlike most globular proteins that are folded into compact
structures, a fibrous protein collagen, has an elongated triple-helix
form.
9. SCHEMATIC VIEW OF AMINO ACIDS IN
COLLAGEN
Simple and complex proteins. Glycoproteins: immunoglobulins.
Hemoglobine. Nucleoproteins. Transcription, translation. Protein
synthesis.
11. From COLLAGEN MOLECULE
to COLLAGEN FIBER
Has high tensile strength
Protects tissues from mechanical damage
𝛼 − 𝑐ℎ𝑎𝑖𝑛
triplet
12. Structure of elastin (scleroprotein)
In contrast to collagen, which forms fibers that are tough
and have high tensile strength to protect the tissues from
mechanical damage, elastin is a connective tissue protein with
rubber-like properties. Elastic fibers composed of elastin and
glycoprotein microfibrils are found in the lungs, the walls of large
arteries, and elastic ligaments. They can be stretched to several
times their normal length but recoil to their original shape when
the stretching force is relaxed. Elastin is an insoluble protein
composed mostly from non-polar amino acids namely glycine,
alanine, valine. Elastin is also rich in proline and lysine but
contains scant hydroxyproline and hydroxylysine.
14. 4 lysins asssociate into unit of elastin,
namely desmosine
Desmosine may be a constituent of 4 elastin molecules
simultaneously, making linkage between these 4
chains.
15. Desmosine connects with molecules of
collagen, hyaluronic acid, adhesive proteins
Desmosine linked with different compounds
collagen
Hyaluronic acid
tanassin
16. Keratin (scleroprotein) in hair
When exposed to mechanical stress, α-
keratin structures can retain their shape and
therefore can protect what they surround.
17. Under high tension, alpha-keratin can even
change into beta-keratin
After heating, α-keratin turns to β-
keratin
α-keratin
18. β-keratin of bird feather
beta-keratin is a stronger keratin formation, that has a secondary structure of beta-pleated
sheets.
20. CURLING OF HAIR is based on cystein
reducing-oxidation properties
21. Blood albumins and globulins: separation of
blood proteins by electrophoresis
Blood albumin does not contain glycocol, its isoelectric point =
4.7, just as isoelectric point of casein (present in milk) and
ovalbumines. The ratio of albumin to globulins in the blood is
referred to as serum protein index, in the norm it is = 1.5 -2.3. Milk
contains lactalbumin; ovalbumin is an egg protein.
𝛼1 𝛼2 𝛽 𝛾 (confront antigen)
23. Each blood fraction comprises the clinically important proteins of
Each blood fraction comprises clinically
important proteins
In blood plasma, haptoglobin binds to free
hemoglobin, compared to hemopexin that binds to
free heme released from erythrocytes with high
affinity, and thereby inhibits its deleterious oxidative
activity. The haptoglobin-hemoglobin complex will
then be removed by the reticuloendothelial system
(mostly the spleen).
24. Globulin fractions are: α1-, α2-, β1-, β2-, γ- globulins.
pseudo globulins
precipitated with 33% solution
of ammonium sulphate
Euglobulins, that precipitate in 50% solution of
ammonium sulphate
30. Celiac disease
Gluten – glutelin
+ prolamin
Normal villi atrophic villi
bloating, flatulence
the intestine
31. Gluten present in most of delicacy:
Gluten is the general term for a protein found
in wheat, barley, rye, and so on. All forms of wheat contain
gluten. Many everyday food products have gluten, such
as pasta, bread.
Beer also comprises gluten.
33. Glycoproteins comprise carbohydrate
moiety:
The carbohydrate component imparts to glycoproteins
specificity and stability to temperature: toward heating
and cooling, protect them from proteolytic enzymes. In
glycoproteins, carbohydrates are linked to serine,
threonine and asparagine of peptide chain.
Asn
Ser
38. Binding of Immunoglobulins (Ig) to B-cell surface (IgM, IgD…)
Membrane-bound immunoglobulins are
associated non-covalently with two accessory
peptides, forming the B-cell antigen receptor
complex. The first antigen receptors expressed by B
cells are IgM and IgD. The receptor is a prototype of
the antibody that the B cell is prepared to produce.
IgE also circulate in blood bound to mast
cells and basophils.
40. Disulfide bond makes the chains flexible
Ig are sort depending on their heavy chains: IgG have gamma (𝛾)-chains; IgM -
mu(𝜇)-chains; IgA - alpha 𝛼-chains; IgE - epsilon (𝜀)- chains; and IgD - delta(𝛿)-
chains.
41. Function of IgA (protects secretions)
IgA is seen in a wide variety of biological
secretions, including milk, saliva, tears and
mucus. Presence of IgA on mucus
membranes makes it an important gate-
keeper in physically vulnerable locations, or
the spots at which microbes might easily find
ways deeper into the body.
In fact, the dimeric form of IgA
is more common. IgA tends to
be non-specific in terms of the
types of foreign presences it
42.
43. IgD
IgD is a monomer, and is
the rarest of the five classes of immunoglobulins
In addition to its role as a cell-surface receptor,
IgD is found to a lesser extent in blood and
lymphatic fluid. It is thought in some people to
react with certain haptens (antigenic subunits) on
penicillin, which is likely why some people are
allergic to this antibiotic; it may also react with
ordinary, normal blood proteins in the same way,
thereby effecting an autoimmune response.
44. IgE – a mediator of allergy, which
facilitates lysis of helmints.
IgE is a mediator of allergic reactions. When an antigen
binds to the Fab portion of an IgE molecule bound to a mast
cell, this causes the mast cell to release histamine into the
bloodstream.
IgE also takes part in the lysis, or chemical degradation,
of parasites of the protozoan variety. Ergo, IgE is made in
response to the presence of helminths.
IgE can protect mucosal surfaces by initiating
inflammation. It tends to cause pain and swelling. Inflammation,
among many its other immune benefits, enables IgG (, which
are proteins from the complement pathways) and white blood
cells to enter tissues to confront antigens.
Like IgD, IgE is a monomer and has two antigenic
binding sites, one on each "arm." It is bound to mast cells and
45. IgG is the dominant antibody in the human body,
accounting about 85 % of all Ig-s
It has the ability to cross placenta in pregnant women, allowing to
protect the unborn fetus and newborn baby.
Its main activities include:
1) enhancing phagocytosis in macrophages (specialized "eater"
cells) and neutrophils (another type of white blood cell)
neutralizing toxins; and
2) inactivating viruses and killing bacteria. It is usually the
second antibody when an invader is present, following closely
behind IgM. Its presence is increased in the body's
anamnestic
response. "Anamnestic" translates to "not forgetting”.
IgG responds to an microbe that has encountered
before, and limits the effects of microbes.
It is found chiefly in the blood and lymph. IgG also exists as a
monomer.
46. COVID19. HIGH SPECIFICITY OF IgG. N-
end provides Ig-Ag recognition
As with other coronaviruses, it appears that after
initial infection, the typical patient will see symptom onset
around 5 day, and IgM antibodies begin to develop
around 8 days post infection and IgG antibodies around
14 days post infection.
47. IgM – the first responder of immune system
IgM exists as a pentamer, or a group of five bound IgM
subunits.
Because IgM is mostly a pentamer, it has 10
epitope-binding sites, making IgM very active. Its
five Fc portions, like those of most other
immunoglobulins, can activate the complement-
protein pathway, and as a "first responder" is the
most efficient type of antibody in this regard. It
promotes phagocytosis and lysis of micro-
organisms. IgM also agglutinates invading material
(sticks pieces together) for easier
clearing from the body.
Monomeric forms of IgM are found chiefly on the surface of B-lymphocytes as
receptors.
48.
49. Myoglobin of muscle:
1 CHAIN + 1 heme with SINGLE IRON
IN IT
HEMEPROTEINS:
MYOGLOBIN, HEMOGLOBIN,
CATALASE…
50. Hemoglobin is a heterotetrameric oxygen transport
protein found in red blood cells (erythrocytes),
whereas myoglobin is a monomeric protein found
mainly in muscle tissue where it serves as an
intracellular storage site for oxygen. Myoglobin has a
higher oxygen affinity at all pO2 values, than does
hemoglobin. Oxygenated (MbO2) and deoxygenated
(Mb) myoglobin exist in a simple equilibrium:
Mb + O2 MbO2
The equilibrium is shifted to the right or to the left as
oxygen is added to or removed from the system.
Myoglobin binds with oxygen, released by hemoglobin
in muscle and, in turn, releases oxygen within the
muscle in response to oxygen demand.
51. In adults, HbA1 (2𝛼2𝛽) is main protein of RBC, as
accounts 95-98% of total blood hemoglobin
52. HEMOGLOBIN properties:
HETEROGENEITY
Main normal hemoglobin types in adult are: Hemoglobin A (Hb A1,
2𝛼2𝛽), which is 95-98% of hemoglobin found in adults and
Hemoglobin A2 (Hb A2: 2𝛼2𝛿), which is 2-3% of hemoglobin found in
adults. Hemoglobin F (Hb F, 2𝛼2𝛾), produced in fetus is found in
adults up to 2.5%.
There is also synthesized the primary hemoglobin (HbP) by the fetus,
called Gover- hemoglobin. Beginning from 2nd week, Hb Gover1
consisting of 2 alpha-like ℶ− and 2beta−like ε− chains is produced
in fetus, while beginning from 6th week, Hb Gover2 of 2 α- and
2 ε−chains is synthesized
53. Hemoglobin (Hb) F is the primary hemoglobin produced from 8th week of fetus up to birth. The
hemoglobin F transports O2 efficiently in a low oxygen environment. This hemoglobin
production stops at birth and decreases to adult levels by the age of one or two. After birth, the
transition from hemoglobin F (α2γ2) to hemoglobin A1 (α2β2) occurs. The γ chain has
considerable structural homology with the β chain, differing in 39 out of 146 amino acids. As
the fetus approaches term, γ-chain synthesis is suppressed as β-chain synthesis is initiated. After
the first few months of life, hemoglobin F normally comprises less than 1 per cent of the red-cell
hemoglobin.
The levels of hemoglobin F can be normal to increased in beta thalassemia. Hemoglobin F
frequently increases in individuals with sickle cell anemia.
56. O2
the rupture of some bonds between the αβ dimers helps to
loading of O2
57. Binding of CO2 with Hb occurs via N-
terminus
In the tissues
58. In the tissues pH is low, in the lungs - high
Bohr effect: the release of oxygen from
hemoglobin is enhanced when the pH is
lowered. Conversely, raising the pH at
lowering of the concentration of CO2 results
in a greater affinity of hemoglobin for
oxygen, stabilizing the R (oxy) form of
hemoglobin.
59. CO connection to Hemoglobin
When incomplete combustion of gas methane occurs, CO
concentration rises in inhaled air and poisoning with carbon
monoxide occur, i.e. formation of tightly bound form of
carboxyHb in the blood. CO is found in fumes produced any time
we burn fuel in cars, fireplaces, gas ranges. CO can build up
indoors and poison people and animals who breathe it.
Formation of carboxyHb in the blood leads to death.
60. The most common symptoms of CO poisoning are
headache, dizziness, weakness, upset stomach,
vomiting, chest pain, and confusion. CO symptoms
are often described as “flu-like.” If you breathe in a
lot of CO it can make you pass out or kill you. People
who are sleeping or drunk can die from CO
poisoning before they have symptoms.
61. BUT 2,3-BPG FACILITATES OXYGEN
RELEASE WITH FORMATHION OF T-Hb
2,3-Bisphosphoglycerate (2,3-BPG) is the most
abundant organic phosphate in the red blood cells
(RBC), where its concentration is approximately that of
hemoglobin. 2,3-BPG is synthesized from an
intermediate of the glycolytic pathway. The
concentration of 2,3-BPG in the RBC increases in
response to chronic hypoxia, such as that observed in
chronic obstructive pulmonary disease like emphysema,
or at high altitudes, where circulating
hemoglobin may have difficulty receiving
sufficient oxygen.
62. Intracellular levels of 2,3-BPG 9 (in RBC)are
also elevated in chronic anemia, in which fewer than
normal RBCs are available to supply the body’s
oxygen needs. Elevated 2,3-BPG level lowers the
oxygen affinity of hemoglobin, permitting greater
unloading of oxygen in the capillaries of the tissues.
To increase the synthesis of 2,3-Bisphospho-
glycerate in transfused blood , inosine is added to it.
63. Loading and unloading of O2 by
Hemoglobin (R- and T-forms)
T form is the deoxy form of hemoglobin called
“T, ” or taut (tense) form. The T conformation is the
low-oxygen affinity form of hemoglobin. This form is
prevalet in the periferic tissues.
R form is the high-oxygen-affinity form of
hemoglobin. The binding of O2 to hemoglobin causes
the rupture of some bonds between the αβ dimers
leading to formation of “R, ” or relaxed structure.
This form is prevalet in the lungs.
65. OxyHb (R) coming from the lungs, is
converted to deoxyHb (T) in the tissues
66. Sickle cell anemia – SICKLE-SHAPED
red blood cells (RBC)
It is a genetic disorder of the blood caused by a single
nucleotide substitution in the gene for β-globin. Sickle cell
anemia is characterized by lifelong episodes of pain (“crises”). A
disease is manifested in the form of chronic hemolytic anemia
with associated hyperbilirubinemia and increased susceptibility
to infections, usually beginning in infancy. Lifetime of a RBC in
sickle cell anemia is less than 20 days, compared with 120 days
for normal RBC, hence, the anemia occur. A molecule of HbS
contains two normal α-globin chains and two mutant β-globin
chains (βS), in which glutamate at position six has been replaced
with valine. This leads to absence of the negatively charged
glutamate residues in the two β chains.
68. Metal ions in metallo proteins:
Fe, Co, Ni, Zn, Ca, Cu etc.
Metal ions participate in oxidation-
reduction reactions: mostly Fe, Cu, Mo
69.
70. Ferritine in spleen, bone marrow, liver
Ferritine is a depot form of iron (III valented)
in these tissues.
The unique structure of ferritin forms a
spherical shell in which the iron is "stored" as
Fe(III) in a crystalline mineral. Ferritin consists
of 24 peptide subunits, that form two types of
channels where these subunits intersect;
the 3-fold channel is polar and the
4-fold channel is nonpolar.
71. β-protein of blood-
Transferrin
It transports iron in III valented form in the
blood. Transferrin is a disulfide-linked
homodimer, that has an iron-bound receptor.
The protein is composed of alpha helices and beta sheets that
form two domains. The N- and C- terminal sequences are
represented by globular lobes and between the two lobes is
an iron-binding site. If patient has a higher amount of
transferrin, he may have iron-deficiency anemia. If
patient has a lower level, he may have another problem,
such as liver disease and hemolytic anemia.
72. Hemosiderin cumulates mostly in the spleen
The breakdown of heme gives rise
to iron. The body then traps the released iron and
stores it as hemosiderin in tissues. Hemosiderin is
also generated from the abnormal metabolic
pathway of ferritin. It is only found within cells and
appears to be a complex of ferritin, denatured
ferritin and other material. The iron within deposits
of hemosiderin is very poorly available to supply
iron when needed.
In norm, hemosiderin
deposits are small.
73. α2- protein of blood,
Ceruloplasmin, transports Cu & participates in
convertion of Fe (3) to Fe (2)
Ceruloplasmin is a protein made in the liver. It
stores and carries the mineral copper around the body.
Ceruloplasmin carries 65% to 90% of the copper found
in blood. Copper is vital to many processes in our body.
These include building strong bones and making
melanin. But having too much copper in the body can be
toxic.
The liver normally takes copper from the
bloodstream and puts it into ceruloplasmin proteins. The
ceruloplasmin is then released into blood plasma.
Ceruloplasmin carries copper around our body to the
tissues that need it.
74. Wilson disease
In Wilson disease, copper is not put into
ceruloplasmin. The disease also keeps the
liver from sending extra copper to be eliminated
in the bowel movements. Instead, copper builds
up in the liver until it overflows into the
bloodstream. From there, copper builds up in
the brain, corneas, kidneys, liver, bones, and
small glands near the thyroid. If not treated, the
liver and brain damage due to copper poisoning
is fatal.
78. Chylomicrons are very large particles that mainly carry
triglycerides (fatty acids from our food). They are made in the
digestive system and so are influenced by what we eat.
Very-low-density lipoprotein (VLDL) particles also carry
triglycerides to tissues. But they are made by the liver. As the
body's cells extract fatty acids from VLDLs, the particles turn
into intermediate density lipoproteins, and, with further
extraction, into LDL particles.
Low-density lipoprotein (LDL) particles are even richer in
pure cholesterol, since most of the triglycerides they carried
are gone. LDL is known as "bad" cholesterol, because it
delivers cholesterol to tissues and is strongly associated with
the buildup of artery-clogging plaque.
«BAD CHOLESTEROL»
79. «GOOD CHOLESTEROL»
High-density lipoprotein (HDL) particles are called
"good" cholesterol because some of them remove
cholesterol from circulation and from artery walls and
return it to the liver for excretion.
HDL is mainly secreted by the liver and small
intestines. The liver, which secretes ~70–80% of
the total HDL in plasma, is the main source
of HDL in the circulation. Apolipoprotein (apo)A is
the major structural protein and constitutes the
framework of HDL to bear phospholipids and
cholesterol.
