Polypeptides

A protein may consist of one or more polypeptide chains. The proteins ribonuclease, chymotrypsinogen, lysozyme and papain consist of single polypeptide chains. These chains are folded and held together by disulphide (-S-S-) bonds. Insulin and trypsinogen consists of two polypeptide chains each. Collagen consists of three polypeptide chains, each in the form of a left-handed helix.