Sulphur-Containing Hormones

Correct Answer: Insulin, Oxytocin and ADH (Vasopressin)

The answer key states 'All the above' referring to (a) Insulin and (b) Oxytocin from the given options. However, Prolactin is NOT a sulphur-containing hormone; it is a protein hormone with no disulphide bonds essential to its structure.

The correct sulphur-containing hormones are:

• Insulin: Contains two disulphide (–S–S–) bonds linking the A and B chains.
• Oxytocin: A nonapeptide with one disulphide bond between cysteine residues at positions 1 and 6.
• ADH / Vasopressin: Structurally similar to oxytocin; also contains a disulphide bond.

Note: The book answer is 'All the above' (a, b, c) — for exam purposes, mark 'All the above' if that option appears, as the book includes Prolactin. The important conceptual point is that sulphur is present as disulphide bridges in peptide hormones.