Structural studies on yeast 3-phosphoglycerate kinase. Isolation by affinity chromatography and characterization of the peptides produced by cyanogen bromide cleavage. Location of the single cysteinyl residue in the primary structure.

Cyanogen bromide cleavage of yeast 3-phosphoglycerate kinase yielded four fragments which account for the amino acid composition of the entire molecule. These results are consistent with a single polypeptide chain of molecular weight 42 000. Affinity chromatography on Sepharose-mercurial followed by gel filtration on Sephadex was used with success for separation of peptides. The carboxyl and N-terminal fragments were characterized. The N-terminal fragment contained the single cysteinyl residue of the protein. After cyanylation and subsequent cleavage, this cysteinyl residue was located near position 100.