Dissecting the Total Transition State Stabilization Provided by Amino Acid Side Chains at Orotidine 5′-Monophosphate Decarboxylase: A Two-Part Substrate Approach

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• 作者：Shonoi A. Barnett ; Tina L. Amyes ; Bryant M. Wood ; John A. Gerlt ; John P. Richard
• 刊名：Biochemistry
• 出版年：2008
• 出版时间：July 29, 2008
• 年：2008
• 卷：47
• 期：30
• 页码：7785-7787
• 全文大小：113K
• 年卷期：v.47,no.30(July 29, 2008)
• ISSN：1520-4995

文摘

Kinetic analysis of decarboxylation catalyzed by S154A, Q215A, and S154A/Q215A mutant yeast orotidine 5′-monophosphate decarboxylases with orotidine 5′-monophosphate (OMP) and with a truncated nucleoside substrate (EO) activated by phosphite dianion shows (1) the side chain of Ser-154 stabilizes the transition state through interactions with the pyrimidine rings of OMP or EO, (2) the side chain of Gln-215 interacts with the phosphodianion group of OMP or with phosphite dianion, and (3) the interloop hydrogen bond between the side chains of Ser-154 and Gln-215 orients the amide side chain of Gln-215 to interact with the phosphodianion group of OMP or with phosphite dianion.