The stereochemical course of phosphoric residue transfer catalyzed by beef heart mitochondrial ATPase

Abstract

The stereochemical course of phosphoric residue transfer has been determined for beef heart mitochondrial ATPase. When aden 5'-(3-thiotriphosphate), stereospecifically labeled with 18O in the gamma position, was hydrolyzed in [17O]water in the presence of the ATPase, the product inorganic [16O, 17O, 18O]thiophosphate was chiral. The configuration of the product showed that the hydrolysis had proceeded with inversion at the gamma-phosphorus atom. This result suggests that there is a direct, in-line transfer of the phosphoric residue between ADP and water and that there is no phosphoenzyme intermediate.