Purification and some properties of phosphorylglyceric acid mutase from rabbit skeletal muscle.

The reversible conversion of 3-phosphoryl-n-glyceric acid (3PGA) into 2-phosphoryl-n-glyceric acid (2PGA) was first shown to occur in rabbit muscle extracts by Meyerhof and Kiessling (1) as one step in the pathway of glycolysis. These authors determined an equilibrium constant for this reaction in crude muscle extracts and showed that only the D(-) isomers of 2PGA and 3PGA were substrates. Although early attempts to purify the enzyme were unsuccessful (1, 2), Sutherland et al. (3) obtained a partially purified preparation and demonstrated the participation of 2,3diphosphorylglyceric acid in the reaction. The present investigations have shown that the enzyme from rabbit muscle is quite stable to most purification procedures and a go-fold purification has been obtained. This preparation was free from enolase, and a direct determination of the equilibrium of the mutase-catalyzed reaction was possible. No metal ion requirement could be demonstrated for this preparation; but the enzyme was inhibited by fluoride and heavy metal ions and by sulfhydryl reagents. As a step toward further study of the mechanism of action of this enzyme, the effects of compounds structurally related to phosphorylglyceric acid have been tested, both as substrates and as inhibitors.