Question

In large proteins such as myoglobin and enzymes, peptide chains are much looped, twisted and folded back on themselves to form a tertiary structure. Which bonds are involved in the formation of tertiary structure of proteins?

• A. Hydrogen bonds.
• B. Peptide bonds.
• C. Disulphide bonds.
• D. Glycosidic bonds.

Hint:

Peptide bonds make the primary structure; the folded tertiary form is held mainly by hydrogen bonds and other weak side-chain interactions.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
The tertiary structure is the overall three-dimensional folding of one polypeptide chain.

Step 2: Rule out wrong bonds
Peptide bonds join amino acids and make only the primary structure.
Glycosidic bonds link sugars, not amino acids.

Step 3: Bonds in tertiary structure
The folding is held by interactions between side chains, chiefly hydrogen bonds, together with ionic and hydrophobic forces.
Myoglobin, the example given, has no disulphide bridges, so the main bonds listed here are hydrogen bonds.

Final Answer:
Hydrogen bonds are involved in forming the tertiary structure. \[ \boxed{\text{(A) }\text{Hydrogen bonds.}} \]