Which of the following peptide chain in not present in mature insulin

Options

A. A-peptide
B. B-peptide
C. C-peptide
D. A & B peptide

Answer

To determine which peptide chain is not present in mature insulin, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Insulin Structure**: Insulin is a peptide hormone composed of chains of amino acids. It is produced in the pancreas and plays a crucial role in regulating blood sugar levels.

2. **Identify Proinsulin**: Insulin is initially synthesized as a precursor molecule called proinsulin. Proinsulin contains three peptide chains: A chain, B chain, and C chain.

3. **Conversion to Mature Insulin**: During the maturation process, proinsulin undergoes enzymatic cleavage. This process removes the C peptide chain, resulting in the formation of mature insulin, which consists only of the A and B chains.

4. **Identify the Peptide Chains in Mature Insulin**: In mature insulin, only the A and B chains remain. The C peptide chain is absent.

5. **Conclusion**: Therefore, the peptide chain that is not present in mature insulin is the C peptide.

### Final Answer:
The peptide chain that is not present in mature insulin is the **C peptide**.

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