Question

Explain in brief structure of insulin.

Answer 1

• Insulin is the hormone that is secreted by the $\beta$- cells in islets of Langerhans. This is a peptide hormone containing 51 amino acids. The amino acids are attached by the peptide bonds.
• There are two polypeptide chains, A and B. The A chain is composed of 21 amino acids and the B chain is composed of 30 amino acids. There are three disulfide bridges which connect the two chains.
• There are bridges between amino acid 7 of A chain (A7) and amino acid 7 of the B chain (B7). There are bridges between A20 and B19, and A6 to A11. This hormone is synthesized in the form of pro-insulin which also contains C-peptide.