Explain the structure of a typical antibody molecule.

Explanation

Structure of antibody : Antibodies are glycoproteins which are highly specific to specific antigens. They are also known as immunoglobulins (Igs). Antibodies are produced by plasma cells which in turn are formed by B-lymphocytes. The plasma cells produce about 2000 molecules of antibodies.

Antibody is a .Y. shaped structure. It consists of four polypeptide chains, two heavy or H chains and two light or L chains. The four polypeptide chains are held together by disulphide Intra and inter chain bonds (-s-s-) to form a .Y. shaped structure. The region holding arms and stem of antibody is termed as hinge. Each chain of the antibody includes two distinct regions, the variable region and the constant region. Variable regions constitute the antigen-binding site. (paratope). This part of antibody recognizes and binds to the specific antigen forming an antigen-antibody complex. Since most antibodies carry two antigen binding sites, they are said to be bivalent.