The effects of anions on phosphoglycerate mutase

Chloride (5-100 mM) can activate the phosphoglycerate mutase reaction (3-PG in equilibrium with 2-PG). I-, N0-3, or higher Cl- inhibit the mutase reaction while allowing mixing of isotope from [32P]3-PG into a large pool of 2,3-bisphosphoglycerate. p-Hydroxybenzoate inhibits without causing isotope dilution. A number of anions (p-hydroxybenzoate approximate equal to NO3- greater than Cl- greater than Tes greater than acetate) stimulate the P-glycolate activated 2,3-bisphosphoglycerate phosphatase reaction of this enzyme. The same anions inhibit competitively with P-glycolate. A kinetic analysis relates the anion effects to changes in rates of association and dissociation of substrates.