Yeast 3-phosphoglycerate kinase: sulfate and substrate binding, their effect on the conformational state of the enzyme

Abstract

Anions, and particularly sulfate, interact with 3-phosphoglycerate kinase and induce an increase of its catalytic efficiency. Information on the location of the anionic site and on the conformational change produced by the sulfate binding was presented. Sulfate is able to modify the environment of some critical amino acids (cysteine and arginines) located in the N-terminal half of the protein, to induce perturbation of aromatic residues as judged by spectrophotometry and to slightly decrease the magnitude of the Cotton effect at 233 nm. All these modifications are produced by sulfate concentrations required for the activation of the enzyme. The most striking result consists in a large change in the hydrodynamic properties of the protein upon sulfate interaction as determined by analytical ultracentrifugation studies. Thus, sulfate modifies the shape of the molecule, causing it to become more compact. A study of the binary and ternary complexes between baker''s yeast 3-phosphoglycerate kinase and its substrates suggests than such a change of the shape of the molecule only occurs in sulfate.sbd.enzyme with or without substrates and in ATP(with or without Mg2+).sbd.3-phosphoglycerate.sbd.enzyme complexes.