Divalent Cation-dependent Stereospecificity of Adenosine 5’-O-(2Zhiotriphosphate) in the Hexokinase and Pyruvate Kinase Reactions

J1P NMR studies with Cd(II) and Zn(II) chelates of adenosine 5’-0-(34hiotriphosphate) (ATPyS) and the Cd(D) chelate of adenosine 5’-O-(24hiotriphosphate) (ATPBS) indicate that these metal ions chelate to the sulfur atom of the thiophosphate group. Since Mg(II) chelates to oxygen of the thiophosphate group of ATPjIS, the configuration of the Mg(II) chelate of one diastereoisomer is equivalent to the configuration of the Cd@) chelate of the opposite diastereoisomer. As a consequence, an inversion of the stereospecificity is observed when Cd(I1) is substituted for Mg(II) in the phosphoryl transfer reactions catalyzed by yeast hexokinase and rabbit muscle pyruvate kinase. When Co(D) is the activating ion for yeast hexokinase with ATP#?S as substrate, no stereospecificity is observed. Since the absolute configuration for the diastereoisomer of CO(III)(NH~)~A’I’P which is the active substrate for yeast hexokinase has been established by Cornelius and Cleland (Cornelius, R. D., and Cleland, W. W. (1978) Biochemistry, in press), the absolute stereochemistry of the Mg(II) complex of the B isomer of ATP/3S is now established by its stereospecificity in the hexokinase reaction.