Question

Regarding secondary structure of a protein, correct statement(s) is/are
A) Peptide bonds possess regional planarity.
B) $C=O$ and $-NH$ of different peptide chains are held by Van der Waal's attractions.
C) They have closely packed arrangement so as to minimise repulsion between R groups.

• A. only C
• B. only B
• C. A and B
• D. only A

Answer 1

The correct option is D only A

Peptide bonds possess regional planarity. For the entire molecule, the long amino acid chains exists in looped, coiled, stretched or folded structure.
Thus, the statement A is correct.

$C=O$ and $-NH$ of different peptide chains are held by intermolecular hydrogen bonds.
Thus, the statement B is incorrect.

Closely packed arrangement is due to hydrogen bonds.
Thus, the statement C is incorrect.

Option D is correct.