Question

What is the structural difference between proinsulin and mature, biologically active insulin?

विकल्प

• Active insulin consists of three separate polypeptide chains linked by peptide bonds

• Active insulin contains an extra C peptide segment that is absent in the proinsulin precursor

• Proinsulin contains an extra stretch called the C peptide, which is removed during maturation into active insulin

• Proinsulin contains only the A chain of 21 amino acids and lacks the B chain

Answer 1

Proinsulin is synthesized as a precursor containing the A chain, B chain, and an extra connecting C peptide. During post-translational processing, the C peptide is removed, leaving active insulin consisting of the A chain (21 amino acids) and B chain (30 amino acids) linked by disulphide bonds.