Disulphide Bond
A covalent bond formed between the sulphur atoms of two cysteine amino acid residues within a peptide or protein. Disulphide bonds stabilise three-dimensional structure and are critical to the function of many therapeutic peptides, including oxytocin and insulin.
Technical Context
Disulphide bonds form through oxidation of thiol (-SH) groups on cysteine residues. They are important structural features in many peptide hormones: oxytocin has one intramolecular disulphide bond forming a 20-membered ring, vasopressin has a similar structure, and insulin has two interchain and one intrachain disulphide bond. The presence of disulphide bonds affects manufacturing (correct bond formation must be ensured during synthesis) and stability (reducing conditions in the GI tract can break these bonds, contributing to poor oral bioavailability). In quality control, disulphide bond integrity is verified through analytical methods including mass spectrometry and peptide mapping.