Question

The structural feature which distinguishes proline from other natural $\alpha$-amino acids is that:

• A. it is optically inactive
• B. it contains aromatic group
• C. it contains two amino groups
• D. it is secondary amine

Answer 1

The correct option is D it is secondary amine

Structure of proline contains a secondary amine group.

Proline is the only amino acid that contains a secondary amine group.