Question

Which of the following is true about human insulin?

• A. Human insulin has two polypeptide chains.
• B. Two polypeptide chains are connected by disulphide bridges.
• C. Proinsulin has A, B and C chains.
• D. All of the above.

Answer 1

The correct option is D

All of the above.

Human insulin is made up of 51 amino acids arranged in two polypeptide chains; A chain with 21 amino acids and B chain with 30 amino acids. The two chains are interconnected by disulphide bridges. In mammals, insulin is synthesised in a pro-enzyme form called pro-insulin. This pro enxyme has both A and B chains and an additional C chain. The Pro insulin is processed, wherein, the C-chain is excised and removed to form the mature insulin enzyme molecule.