A. It is composed of approximately 30 percent proline and hydroxyproline and 30 percent glycine

B. This protein has three chains, each with a conformation very similar to that of polyproline (left handed), are twisted about each other to make a triple helix

C. The three strands are hydrogen bonded to each other, through hydrogen bonds between the -NH of glycine residues and the C=O groups of the other amino acids

D. All three strands are coded by same gene E. Non-covalent interactions mainly stabilize collagen

structure Which of the following statements are correct?

• (A) A, B and C
• (B) A, C and D
• (C) B, C and E
• (D) B, D and E

Solution

A. It is composed of approximately 30 percent proline and hydroxyproline and 30 percent glycine. This statement is correct. Collagen is rich in proline, hydroxyproline, and glycine residues.

B. This protein has three chains, each with a conformation very similar to that of polyproline (left handed), are twisted about each other to make a triple helix. This statement is correct. Collagen has a triple-helical structure, where three polypeptide chains, each with a left-handed polyproline II-type helix, are twisted around each other to form a right-handed triple helix.

C. The three strands are hydrogen bonded to each other, through hydrogen bonds between the -NH of glycine residues and the C=O groups of the other amino acids. This statement is correct. The three polypeptide chains in the collagen triple helix are stabilized by hydrogen bonds between the -NH of glycine residues and the C=O groups of the other amino acids. Statements D and E are incorrect:

D. All three strands are coded by the same gene. This is not correct. The three polypeptide chains in collagen are encoded by different genes.

E. Non-covalent interactions mainly stabilize collagen structure. This is not correct. While non-covalent interactions, such as hydrogen bonds, contribute to the stability of the collagen structure, covalent cross-links between the polypeptide chains also play a crucial role in stabilizing the collagen structure.

Therefore, the correct answer is option A