A biochemical analysis of a hormone extracted from a human pancreas reveals that it consists of two short polypeptide chains, A and B, which are linked together by disulphide bridges. The molecule completely lacks the extra stretch of C-peptide. Identify the specific molecule described.

Step-by-step solution

Insulin is synthesized as a pro-hormone (pro-insulin) which contains an extra stretch called the C-peptide. During maturation into the fully active hormone, the C-peptide is removed. Therefore, a molecule consisting only of polypeptide chains A and B linked by disulphide bridges, and lacking the C-peptide, is mature insulin. Option 1 is incorrect because pro-insulin contains the C-peptide. Option 2 is incorrect because glucagon is a different pancreatic hormone with a different structure. Option 4 is incorrect beca