Multiple isotope effects as a probe of proton and hydride transfer in the 6-phosphogluconate dehydrogenase reaction.
Primary solvent deuterium, primary substrate deuterium, multiple solvent deuterium/substrate deuterium, and multiple solvent deuterium/13C isotope effects on V/K6PG have been measured for the Candida utilis and sheep liver 6-phosphogluconate dehydrogenases (6PGDH). Proton inventory data suggest the presence of a significant medium effect in a step preceding hydride transfer and the presence of a kinetic solvent deuterium isotope effect on hydride transfer. Multiple isotope effect data confirm the presence of multiple solvent deuterium sensitive steps, likely including a conformational change preceding hydride transfer, hydride transfer, and decarboxylation.
Hwang
C C
CC
Department of Chemistry and Biochemistry, University of Oklahoma, Norman 73019, USA.
Cook
P F
PF
D000818:Animals; D002175:Candida / Q000201:enzymology; D002247:Carbon Isotopes; D003903:Deuterium / Q000737:chemistry*; D004579:Electron Transport; D005656:Fungal Proteins / Q000737:chemistry; D006859:Hydrogen; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D010734:Phosphogluconate Dehydrogenase / Q000737:chemistry*; D011522:Protons; D012756:Sheep; D012997:Solvents; D013379:Substrate Specificity
D002247:Carbon Isotopes; D005656:Fungal Proteins; D011522:Protons; D012997:Solvents; D006859:Hydrogen; D003903:Deuterium; D010734:Phosphogluconate Dehydrogenase