Stereochemical course of a phosphokinase using a chiral [18O]phosphorothioate. Comparison with the transfer of a chiral [16O,17O,18O]phosphoryl group.

Synthetic adenosine 5'-O-[3-18O,3-thio]triphosphate having the R configuration at the gamma-phosphorus has been used as a substrate in the reaction catalyzed by glycerol kinase. The product sn-glycerol 3-[18O]phosphorothioate has been isolated, and the configuration at phosphorus has been determined by ring closure to the two diastereoisomeric cyclic 2,3-phosphorothioates of sn-glycerol and analysis of the 18O content of each diastereoisomer. The structural identity of these diastereoisomers has been determined by correlation with one of the corresponding diastereoisomers of the cyclic 2,3-phosphorothioate of D-glycerate, whose crystal structure is reported here. From these experiments it is evident that glyc:rol kinase catalyzes the transfer of a thiophosphoryl group with inversion of the configuration at phosphorus, in gratifying agreement with the result from the transfer of a chiral [16O,17O,18O]phosphoryl group [Blättler, W. A., & Knowles, J. R. (1979) J. Am. Chem. Soc. 101, 510].