Question

Why is an antibody molecule represented as H2L2?

Answer 1

Hint: An antibody is also known as an immunoglobulin molecule (Ig). It is a large molecule which is a Y shaped protein and used by the immune system to identify the foreign substances. The antibody identifies the unique molecule of the pathogen called an antigen. Each tip of the antibody contains a paratope that is specific for one particular epitope and allows these structures to bind together with an accuracy.

Complete answer:
There are four polypeptide chains in each antibody molecule. Out of these four chains, two are longer and called as heavy chains and two are smaller and called as light chains. Thus the molecules of antibody are represented by H2L2. Both the chains are arranged in the shape of Y.

Our body produces different types of antibodies like IgA, IgM, IgE and IgG, etc.

Immunoglobulins are globular proteins present in the serum. They are mainly produced by plasma B cells that are used by the immune system of our body to neutralize the entry of foreign particles.

It constitutes about 20-25% of total serum. The single immunoglobulin consists of four linear polypeptide chains. Both the chains are connected through disulfide bonds.

Note:
The interaction between two dimers through hydrogen bonds, disulfide bonds and hydrophobic bonds create a tetramer. The variable region of both heavy and light chains consists of 100-110 amino acids.