OMP Decarboxylase: Phosphodianion Binding Energy Is Used To Stabilize a Vinyl Carbanion Intermediate

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• 作者：Bogdana Goryanova ; Tina L. Amyes ; John A. Gerlt ; John P. Richard
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：May 4, 2011
• 年：2011
• 卷：133
• 期：17
• 页码：6545-6548
• 全文大小：772K
• 年卷期：v.133,no.17(May 4, 2011)
• ISSN：1520-5126

文摘

Orotidine 5鈥?monophosphate decarboxylase (OMPDC) catalyzes the exchange for deuterium from solvent D₂O of the C-6 proton of 1-(尾-d-erythrofuranosyl)-5-fluorouracil (FEU), a phosphodianion truncated product analog. The deuterium exchange reaction of FEU is accelerated 1.8 脳 10⁴-fold by 1 M phosphite dianion (HPO₃^{2鈭?/sup>). This corresponds to a 5.8 kcal/mol stabilization of the vinyl carbanion-like transition state, which is similar to the 7.8 kcal/mol stabilization of the transition state for OMPDC-catalyzed decarboxylation of a truncated substrate analog by bound HPO₃2鈭?/sup>. These results show that the intrinsic binding energy of phosphite dianion is used in the stabilization of the vinyl carbanion-like transition state common to the decarboxylation and deuterium exchange reactions.}