Expression of mutated pea vicilins by yeast

Site directed mutagenesis has been used to introduce two cysteine residues into two hydrophilic regions of the pea vicilin polypeptide previously expressed in Saccharomyces cerevisiae. The mutated polypeptide has been expressed. The resultant protein has been characterised by SDS-Polyacrylamide gel electrophoresis (PAGE) and the presence of both inter- and intra-polypeptide sulphydryl bonds is indicated by bands of different mobility from those of the native protein. The association of mutated vicilin polypeptides into disulphide-bonded aggregates under non-denaturing conditions is not a random process, trimers being the major species produced.