Disulphide structure of a sunflower seed albumin: conserved and variant disulphide bonds in the cereal prolamin superfamily.

Disulphide mapping of a methionine-rich 2S albumin from sunflower seeds showed four intra-chain disulphide bonds which are homologous with those in a related heterodimeric albumin from lupin seeds (conglutin delta). Similar conserved disulphide bonds are also present in alpha-gliadin and gamma-gliadin storage proteins of wheat, but a lower level of conservation is present in a further related group of proteins, the cereal inhibitors of alpha-amylase and trypsin. These differences may relate to the different functions of the proteins.