C-peptide of human insulin is

Options

A. a part of mature insulin molecule
B. responsible for formation of disulphide bridges
C. removed during maturation of pro-insulin to unsulin
D. responsible for its biological activity .

Answer

### Step-by-Step Solution:

1. **Understanding Insulin Structure**:
- Human insulin is a protein composed of two polypeptide chains: the A chain (21 amino acids) and the B chain (30 amino acids).
- These chains are linked together by disulfide bonds.

2. **Prohormone Form**:
- Insulin is synthesized in a prohormone form, which is an inactive precursor that needs to be processed to become active.
- The gene responsible for insulin synthesis is located on chromosome 11.

3. **C-peptide Role**:
- The prohormone form of insulin contains an additional segment known as the C-peptide.
- The C-peptide is crucial during the processing of proinsulin into mature insulin.

4. **Maturation Process**:
- During the maturation of proinsulin to insulin, the C-peptide is removed.
- Mature insulin does not contain the C-peptide.

5. **Conclusion**:
- The C-peptide of human insulin is removed during the maturation of proinsulin to insulin. Therefore, it is not a part of the mature insulin molecule.

### Final Answer:
The C-peptide of human insulin is **removed during maturation of proinsulin to insulin**.

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