Mechanism of the Orotidine 5′-Monophosphate Decarboxylase-Catalyzed Reaction: Importance of Residues in the Orotate Binding Site
作者:Vanessa Iiams、Bijoy J. Desai、Alexander A. Fedorov、Elena V. Fedorov、Steven C. Almo、John A. Gerlt
DOI:10.1021/bi2012355
日期:2011.10.4
The reaction catalyzed by orotidine 5′-monophosphate decarboxylase (OMPDC) is accompanied by exceptional values for rate enhancement (kcat/knon = 7.1 × 1016) and catalytic proficiency [(kcat/KM)/knon = 4.8 × 1022 M–1]. Although a stabilized vinyl carbanion/carbene intermediate is located on the reaction coordinate, the structural strategies by which the reduction in the activation energy barrier is
由 orotidine 5'-单磷酸脱羧酶 (OMPDC) 催化的反应伴随着特殊的速率增强值 ( k cat / k non = 7.1 × 10 16 ) 和催化效率 [( k cat / K M )/ k non = 4.8 × 10 22 M –1 ]。尽管稳定的乙烯基负碳离子/卡宾中间体位于反应坐标上,但实现活化能垒降低的结构策略仍未完全了解。该实验室最近报告说,来自 OMPDC 中的 Asp 70 使“底物不稳定”Methanothermobacter thermoautotrophicus (MtOMPDC) 将活化能势垒降低~5 kcal/mol(对速率提高贡献~2.7 × 10 3)[Chan, KK, Wood, BM, Fedorov, AA, Fedorov, EV, Imker, HJ, Amyes , TL, Richard, JP, Almo, SC 和 Gerlt