ORGN 663 |
| Phosphite dehydrogenase (PTDH) is a unique NAD+-dependent enzyme that catalyzes the oxidation of inorganic phosphite to phosphate. Previous mechanistic studies have found significant kinetic isotope effects (KIEs) in PTDH. To evaluate the degree to which the hydride transfer is rate limiting in PTDH, pre-steady state studies were performed on the WT enzyme and several active site mutants. Pre-steady state studies with the WT and several active site mutants show no burst in the pre-steady state, indicating that slow steps after hydride transfer do not limit the rate of reaction. The pre-steady state KIEs are within error of the steady state DV. Together the pre-steady state KIEs and the absence of a burst in the pre-steady state suggest that the hydride transfer step is fully rate determining in WT PTDH and the active site mutants. This suggests that the observed KIE may be the intrinsic effect. |
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Asymmetric Reactions, Combinatorial Chemistry, Molecular Recognition and Self-Assembly, Proteins, Peptides, Amino Acids and Enzyme Inhibitors
8:00 PM-10:00 PM, Wednesday, March 28, 2007 Hyatt Regency Chicago -- Riverside Center, Poster
Division of Organic Chemistry |