Antibody: Structure and Function
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The document provides an overview of antibodies, detailing their structure, history, and functions. It explains the molecular composition of antibodies, including heavy and light chains, and describes the five classes of antibodies (IgG, IgM, IgA, IgD, IgE) along with their specific functions. Key historical milestones and references are also included.
![3. STRUCTURE
All antibodies share a basic structure
Antibodies are heavy globular plasma proteins[or]
glycoproteins.
The attached glycans are critically important to the
structure and function of the antibody.
Each antibody is heterodiamer with a molecularweight
of approximately 150KD.](https://image.slidesharecdn.com/antibody-190128191452/85/Antibody-Structure-and-Function-5-320.jpg)
![4. IMMUNOGLOBULIN DOMAINS
• Antibody is composed of two identical heavy polypeptide
chains and two identical light chains, bonded via interchain
disulphide[s-s] Linkages.
• Each chain is composed of structural domains called
Immunoglobulin domains.
• These domains contains about 70-110 aminoacids.](https://image.slidesharecdn.com/antibody-190128191452/85/Antibody-Structure-and-Function-9-320.jpg)
Antibody: Structure and Function
- 1. Mr. RAJENDRA SINGH Jr. Biotechnology Network
- 2. SYNOPSIS – 1. Introduction 2. History 3. Structure of Antibody - Basic structure of antibody - sites of immunoglobulin 4. Immunoglobulin Domains - Heavy chain - Light chain 5. Different classes and function of Ab 6. References
- 3. 1. Introduction - Antibody is a large protein, constitiutes γ-globulin produced by plasma cells. It is used by the immune system to identify and nutralize pathogens such as bacteria and viruses. Antibodies are also called Immunogloublins. The antibody recognizes a unique molecule of the harmful agent called ANTIGEN,via the variable region.
- 4. 2. History By 1959 Gerald Edelman and Rodney Porter independently published the molecular structure of antibodies for which they were later jointly awarded the Nobel Prize in 1972. The first atomic resolution structure of an antibody fragment was published in 1973.
- 5. 3. STRUCTURE All antibodies share a basic structure Antibodies are heavy globular plasma proteins[or] glycoproteins. The attached glycans are critically important to the structure and function of the antibody. Each antibody is heterodiamer with a molecularweight of approximately 150KD.
- 6. Basic structure of Antibody
- 9. 4. IMMUNOGLOBULIN DOMAINS • Antibody is composed of two identical heavy polypeptide chains and two identical light chains, bonded via interchain disulphide[s-s] Linkages. • Each chain is composed of structural domains called Immunoglobulin domains. • These domains contains about 70-110 aminoacids.
- 10. HEAVY CHAINS o Five types of heavy chains are present o They are;1) alpha (α) 2) gamma (γ) 3) delta (Δ) 4) epsilon 5) mu (μ) o Each heavy chain has two regions, one constant region and one variable region. o Alpha and gamma chains contains approximately 450 aminoacids, where as mu and epsilon chains have approximately 550 aminoacids.
- 11. LIGHT CHAINS o Two types of light chains are present o They are; 1) kappa 2) lambda o All antibodies have one of the two kinds of light chains. o A light chain has two successive domains, one constant domain and one variable domain. o The approximate length of a light chain is 211-217 aminoacids.
- 12. 5. DIFFERENT CLASSES AND FUNCTION OF ANTIBODIES There are five classes of antibodies are present They are; 1) IgG 2) IgM 3) IgA 4) IgD 5) IgE The antibody classes are named as correspond to their heavy chain types
- 13. 1)IgG • They makes up approximately 80% of the serum antibodies • They has a half-life of 7-23 days • IgG is a monomer and has 2-epitope binding sites • This is the only class of antibodies that can cross the placenta and enter the fetal circulation Functions i. Immunity to new born ii. Neutralisation ofToxins iii. IgG3 binds to Fc receptor by Phagocytosis
- 14. 2)IgM • They makes up approximately 13% of the serum antibodies • They has a half-life of about 5 days • Most of the IgM are pentamer and has 10 - epitope binding sites. some are monomer • It is the first immunoglobulin class produced in a primary response to antigen functions i. Activation of classical pathway ii. Defence against multivalent antigens iii. Act as Opsonin
- 15. 3)IgA • They makes up approximately 6% of the serum antibodies • They has a half-life of approximately 5 days • IgA is a dimer and has 4-epitope binding sites • They found mainly in body secretions such as saliva, mucous, tears, colostrum and milk Functions i. It as a Secretory antibody ii. Effective against virus that causing Influnza iii. Production to Infant gut
- 16. 4)IgD • They makes up approximately 0.2% of the serum antibodies • IgD is a monomer and has 2-epitope binding sites • This class antibodies are found on the surface of B-lymphocytes Function i. B cell activation. ii. Act a receptor for antigen binding
- 17. 5)IgE • It was discovered in 1966 by K. Ishizaka. • It is very low concentration in blood(17-450ng/ml) • It contain small percentage of Lympocytes Functions i. Responsible for Immediate hypersensitivity ii. Binds to Fc receptor on basophils and mast cells iii. Release of substance like histamine ,vasoactive mediators
- 19. References – 1. Immunology- Kuby, 5th Edition, W. H. Freeman and Company • NewYork 2. Immunobiology:The Immune System in Health and Disease. 5th edition, Janeway CA Jr,Travers P, Walport M, et al. NewYork: Garland Science; 2001. 3. Immunology- Fatima et Al. 4. WWW. Google.co.in/picture
- 20. THANKYOU