Question

During the processing of proinsulin into mature insulin :

• A. C peptide is added to proinsulin
• B. C peptide is removed from proinsulin
• C. B peptide is added to proinsulin
• D. B peptide is removed from proinsulin

Hint:

In recombinant DNA technology (Humulin), the A and B chains are produced separately in E. coli and then joined by disulphide bonds to bypass the natural C-peptide removal step.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Insulin is synthesized in mammals as a pro-hormone (proinsulin) that requires processing to become a functional mature hormone.
Step 2: Detailed Explanation:
Proinsulin consists of three chains: A-peptide, B-peptide, and a connecting C-peptide.
Mature functional insulin consists only of A and B chains linked together by disulphide bridges.
During the maturation of proinsulin into insulin, the C-peptide is enzymatically removed.
This is why mature insulin does not contain the C-peptide.
Step 3: Final Answer:
The C-peptide is removed during the maturation process of insulin.