Download MendeleyOn the mechanism of the reaction catalyzed by glucose 6-phosphate dehydrogenase.
Cosgrove, M.S., Naylor, C., Paludan, S., Adams, M.J., Levy, H.R.(1998) Biochemistry 37: 2759-2767
- PubMed: 9485426
- DOI: https://doi.org/10.1021/bi972069y
- Primary Citation of Related Structures:
2DPG - PubMed Abstract:
The catalytic mechanism of glucose 6-phosphate dehydrogenase from Leuconostoc mesenteroides was investigated by replacing three amino acids, His-240, Asp-177, and His 178, with asparagine, using site-directed mutagenesis. Each of the mutant enzymes was purified to homogeneity and characterized by substrate binding studies and steady-state kinetic analyses. The three-dimensional structure of the H240N glucose 6-phosphate dehydrogenase was determined at 2.5 A resolution. The results support a mechanism in which His-240 acts as the general base that abstracts the proton from the C1-hydroxyl group of glucose 6-phosphate, and the carboxylate group of Asp-177 stabilizes the positive charge that forms on His-240 in the transition state. The results also confirm the postulated role of His-178 in binding the phosphate moiety of glucose 6-phosphate.
Organizational Affiliation:
Department of Biology, Syracuse University, Syracuse, New York 13244, USA.
