kahe tsüsteiini jäägi väävli aatomite vaheline kovalentne side, mis ühendab erinevaid polüpeptiide või sama polüpeptiidi erinevaid osi, Disulfide bonds in proteins are formed between the thiol groups of cysteine residues by the process of oxidative folding. They connect different polypeptides or different parts of the same polypeptide.