Insulin Hexamers with Two Zn Atoms

The hormone insuline is comprised of two relatively short peptide chains. In its storage form, it is hexameric and has two (or four) zinc atoms, which are important for its structure.

The octahedral coordination of the zinc atoms is taken over by three histidine residues of different insulin dimers and three water molecules.

  Coordination of the Zn²⁺ ions