¹⁸O Kinetic Isotope Effects Reveal an Associative Transition State for Phosphite Dehydrogenase Catalyzed Phosphoryl Transfer.

ABSTRACT: Phosphite dehydrogenase (PTDH) catalyzes an unusual phosphoryl transfer reaction in which water displaces a hydride leaving group. Despite extensive effort, it remains unclear whether PTDH catalysis proceeds via an associative or dissociative mechanism. Here, primary ²H and secondary ¹⁸O kinetic isotope effects (KIEs) were determined and used together with computation to characterize the transition state (TS) catalyzed by a thermostable PTDH (17X-PTDH). The large, normal ¹⁸O KIEs suggest an associative mechanism. Various transition state structures were computed within a model of the enzyme active site and ²H and ¹⁸O KIEs were predicted to evaluate the accuracy of each TS. This analysis suggests that 17X-PTDH catalyzes an associative p

SUBMITTER: Howe GW 

PROVIDER: S-EPMC6467793 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature