Maturation of proinsulin into insulin takes place after

Options

A. Joining of c-peptide
B. Removal of c-peptide
C. Removal of disulphide bridge
D. Addition of disulphide bridge

Answer

**Step-by-Step Solution:**

1. **Understanding Proinsulin**: Proinsulin is an inactive precursor of insulin. It consists of a single polypeptide chain that includes the A and B chains of insulin, connected by a C-peptide.

2. **Structure of Proinsulin**: The proinsulin molecule has three parts: the A chain, the B chain, and the C-peptide. The C-peptide is crucial for the maturation process.

3. **Maturation Process**: The maturation of proinsulin into insulin involves specific enzymatic reactions. The C-peptide is cleaved from the proinsulin molecule by specific peptidases.

4. **Role of C-Peptide**: During maturation, the C-peptide is removed, which allows the A and B chains to come together and form the active insulin molecule.

5. **Final Structure of Insulin**: After the removal of the C-peptide, the A and B chains of insulin can form disulfide bridges, stabilizing the structure. Insulin is then stored in the pancreas as a hexamer, which is stabilized by zinc ions.

6. **Conclusion**: The correct answer to the question is that the maturation of proinsulin into insulin takes place after the removal of the C-peptide.

**Final Answer**: The maturation of proinsulin into insulin takes place after the removal of the C-peptide.

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