Antibody

Classification of Antibodies

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Assignment of Microbiology

Topic


Submitted to

Dr. Khalid Mahmmod

Submitted by

M. Umair

Bs(H) Zoology

Semester First

Roll No 2014-AZ-034

UVAS Ravi Campus(Pattoki )

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Antibody

Definition Antibodies are globulin proteins (a protein family with a compact, globular form)-therefore, we have come to use the term immunoglobulin(Ig) for antibodies. Globulin proteins are relatively soluble.

Antibodies are made in

response to an antigen and can recognize and bind to the antigen. A bacterium or virus may have several epitopes that cause the production of different antibodies. Each antibody has at least two identical sites that bind to epitopes. These sites are known as antigen-binding sites.

Valence of Antibody

The number of antigen-binding sites on an antibody is called the valence of that antibody.

For example, most human antibodies have two binding sites; therefore, they are

bivalent

classification of Antibodies The simplest and most abundant immunoglobulin are in size and monomers, but they can also assume some differences arrangement.

The five classes of Igs are designated

The five classes of antibodies are following

1. Ig G,(Immunoglobulin G)2. Ig M,(immunoglobulin M)

3. Ig A,(Immunoglobulin A)4. Ig D,(Immunoglobulin D)5. Ig E.(Immunoglobulin E)

These are classified by the kind of heavy chain found in the molecule.

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Classification of Antibodies Ig G molecules contain heavy chains known as gamma chains Ig M molecules contain heavy chains known as mu-chains Ig A molecules contains heavy chains known as alpha chains Ig D molecules contains heavy chains known as delta chains Ig E molecules contains heavy chains known as epsilon chains

The difference which is present in heavy chain polypeptides permit these antibodies to work in difference kinds of immune responses and at special stages of the immune response.

The structures of Ig G,Ig D, and Ig E molecules resembles. Molecules of IgA and Ig M are aggregates of two or five monomers, respectively, that are joined together.

Explanation of different classes

Explanation of Immunoglobulin G

Ig G (the name is derived from the blood fraction gamma globulin) accounts for about 80% of all antibodies in serum. In regions of inflammation these monomer antibodies readily cross the walls of

blood vessels and enter tissue fluids. . Maternal Ig G antibodies, for example, can cross the placenta and confer passive immunity to a fetus Ig G antibodies protect against circulating bacteria and viruses, neutralize bacterial toxins, trigger the complement system, and, when bound to antigens, enhance the effectiveness of phagocytic cells

Properties of Ig G Antibody

1. Molecular weight 1500002. .Serum concentration 10 to 16mg/mL3. Glycosylation(by weight) 3%4. Percent of total antibodies 75%)

Heavy chain type

Gamma chain (53000

Distribution, 4

Classification of Antibodies Intra and extravascular

Function

Secondary response

Explanation of Immunoglobulin MIgM Antibodies of the IgM (from macro, reflecting their large size) class make up 5- 10% of the antibodies in serum. IgM has a pentamer structure consisting of five monomers held together by a

polypeptide called a J (joining) chain. The large size of the molecule prevents Ig M from moving about as freely as Ig G does, so Ig M antibodies generally remain in blood vessels without entering the surrounding tissues. Ig M is the predominant type of antibody involved in the response to the ABO blood group antigens on the surface of red blood cells. It is much more effective than Ig G in causing the clumping of cell s and viruses and in reactions involving the activation of complement. The fact that Ig M appears first in response to a primary infection and is relatively short -lived makes it uniquely valuable in the diagnosis of disease. If high concentrations of Ig M against a pathogen are detected in a patient, it is likely that the disease observed is caused by that pathogen. The detection of Ig G, which is relatively long-lived, may indicate only that immunity against a particular pathogen was acquired in the more distant past

Properties of Ig M antibody

1. Molecular weight 900002. Serum concentration 0.5 to 2mg/ml3. Percent of total antibodies 10%4. Glycosylation (by weight) 12%

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Classification of AntibodiesHeavy chain type

Mu chain (65000)

Distribution

Mostly intravascular

Function

Primary response

Explanation of Immunoglobulin A

IgA accounts for only about 10-15% of the antibodies in serum, but it is by far the most common form

in mucous membranes and in body secretions such as mucus, saliva, tears, and breast milk. If we

take this into consideration, IgA is the most abundant immunoglobulin in the body (lgG is the most

abundant in serum). The form of IgA that circulates in serum, serum IgA, is usually in the form of a

monomer. The most effective

form of IgA, however, consists of two connected monomers that form a dimer called secretory IgA.

It is produced in this form by plasma cell s in the mucous

membranes. Each dimer then enters and passes through a mucosal cell, where it acquires a

polypeptide called a secretory component that protects it from enzymatic degradation. . The main

function of secretory IgA is probably to prevent the attachment of microbial pathogens to mucosal

surfaces. This is especially important in resistance to intestinal and respiratory pathogens. Because

IgA immunity is relatively short-lived, the length of immunity to many respiratory infections is

correspondingly short. IgA's presence in a mother's milk, especially the colostrum page probably

helps protect infants from gastrointestinal infections6


. Properties of Immunoglobulin A

1. Molecular weight 320000

2. Percent of total antibodies 15%

3. Serum concentration 1 to 4mg/ml

4. Glycosylation (by weight) 10%

Heavy chain type

Alpha chain (5500)

Distribution

Intravascular and secretion

Function

Protect mucous membranes

Explanation of immunoglobulin D

IgD antibodies make up only about 0.2% of the total serum antibodies. Their structure resembles that

of IgG molecules. IgD antibodies are found in blood, lymph, and particularly on the surfaces of B

cells. IgD has no well-defined function

Properties of Immunoglobulin D7

Classification of Antibodies1. ) % Percent of total anti bodies 0.2%

2. Glycosylation (by weight) 13


4. Serum concentration 0 to 0.4mg/ml

Heavy chains type

Delta chain (70000

Distribution

Lymphocyte surface

Function

Unknown

Explanation of Antibody E

Antibodies of the IgE class are slightly larger than IgG molecules; they constitute only 0.0002% of the

total serum antibodies. IgE molecules bind tightly by their Fe (stem) regions to receptors on mast

cells and basophils, specialized cells that participate in allergic reactions.

When an antigen such as pollen cross-links with the IgE anti -

bodies attached to a mast cell or basophil, that cell releases histamine and other chemical mediators.

However, the response can be protective as well, for it attracts. These chemicals provoke a

response-for example, an allergic reaction such as high fever complement and phagocytic cells. This 8

Classification of Antibodiesis especially useful when the antibodies bind to parasitic worms. The concentration of IgE is greatly

increased during some allergic reactions and parasitic infections, which is often diagnostically useful.

Properties of Immunoglobulin E

1. Serum concentration 0.002to 400mg/ml

2. Percent of total antibodies 10 %


4. Glycosylation (by weight) 12%

Heavy chain type

Epsilon chain (73000)

Distribution

Basophils and most cells in saliva and nasal secretion

Function

Protect against parasites

This is very simple classification of antibodies which help us while, studying

the function of different types of antibody .

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Summary

Reference

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1. Gerard J. Tortora, , Berdell R. Funke, Micro Biology AN INTRODUCTION TENTH

EDITION

2. Biology Part 1 F.sc Punjab text book

3. /www.google.com.pk/search?

q=classes+of+antibodies&biw=1024&bih=643&tbm=isch&tbo=u&source=u

4. http://www.piercenet.com/method/antibody-structure-classes

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Antibody

Health & Medicine

Transcript of Antibody