STRUCTURAL STUDIES ON YEAST 3-PHOSPHOGLYCERATE KINASE: Linear Arrangement of the CNBr Fragments, Partial Amino Acid Sequence of the Inner Part of the Polypeptide Chain, and Analyses of the N-Terminal Domain of the Protein

The purpose of this work was to contribute to the study of the covalent struc ture of yeast 3‐phosphoglycerate kinase. First, we undertook the complete align ment of the four fragments produced by cyanogen‐bromide cleavage and which constitute the intact protein; we then established the total amino acid sequence of a 30‐residue peptide and the N‐terminal sequence of a 65‐residue peptide. Second, we analyzed the acetylated state of the protein. The analyses of the acid fraction “P” obtained after digestion of 3‐phosphoglycerate kinase by pronase enabled us to determine the N‐terminal sequence of this enzyme as N‐acetylserylglycine. Third, we isolated, purified and analyzed seven tryptic peptides from a fragment containing 102 amino acids coming from the N‐terminal end of the protein. The peptides occupying the N‐ and C‐terminal ends of this fragment were also identified.