Disulfide Bond
Also known as: disulphide bond · disulfide bridge · S-S bond · cystine bridge
A covalent bridge between two cysteine side chains that locks a peptide’s three-dimensional shape in place.
A disulfide bond is a covalent link (–S–S–) formed between the sulfur-containing side chains of two cysteine residues. It is one of the few covalent bonds that stabilise a folded peptide beyond the backbone itself.
Disulfide bonds pin loops and folds into place and greatly increase stability. Many bioactive peptides and hormones depend on one or more disulfide bridges for their shape and activity; disrupting them (reduction) can unfold and inactivate the molecule.
RELATED TERMS
Amino Acid
The building-block molecules of peptides and proteins; each contributes one residue to the chain.
Secondary & Tertiary Structure
The levels of peptide/protein organisation: sequence (primary), local folds (secondary), 3-D shape (tertiary), assembly (quaternary).
Side Chain (R Group)
The variable "R group" on each amino acid that gives it its chemical character — charge, size and water-affinity.
Cyclic Peptide
A peptide whose chain is joined into a ring, giving greater stability and often better receptor selectivity.
Amino-Acid Sequence
The specific order of amino-acid residues in a peptide — its "primary structure" — which dictates shape and activity.
Educational content, not medical advice. All products supplied for research purposes only — not for human consumption.