Question

Which of the following peptides is cyclic in nature?

• A. Oxytocin
• B. Insulin
• C. Glucagon
• D. Vasopressin

Hint:

Oxytocin is cyclic, whereas insulin and other peptides are linear or have chain connections.

Answer 1

The Correct Option is A

Oxytocin is a cyclic peptide consisting of nine amino acids. It forms a cyclic structure through a disulfide bond between cysteine residues, which is crucial for its biological activity. Insulin, glucagon, and vasopressin are not cyclic peptides. Insulin consists of two chains linked by disulfide bonds but does not form a cyclic structure. Thus, the correct answer is (a) Oxytocin.