Transition state structure of Salmonella typhimurium orotate phosphoribosyltransferase.
Transition state structure of Salmonella typhimurium orotate phosphoribosyltransferase.
复制标题
鼠伤寒沙门氏菌乳清酸磷酸核糖基转移酶的过渡态结构。
DOI：
10.1021/bi951898l
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Blanchard,JS
中科院分区：
文献类型：
--
作者：
Tao,W;Grubmeyer,C;Blanchard,JS
Orotate phosphoribosyltransferase (OPRTase) catalyzes the magnesium-dependent conversion of α-d-phosphoribosylpyrophosphate (PRPP) and orotate to orotidine 5‘-monophosphate (OMP) and pyrophosphate. We have determined kinetic isotope effects on the reaction of OMP with pyrophosphate and with the pyrophosphate analog phosphonoacetic acid. In the latter case, full expression of the kinetic isotope effects allowed us to calculate the structure of the transition state for the pyrophosphorylytic reaction. The transition state resembles a classical oxocarbonium ion. Using the recently reported three-dimensional structures of the OPRTase−OMP (Scapin et al., 1994) and the OPRTase−PRPP complexes (Scapin et al., 1995a), we have modeled the calculated transition state structure into the active site of OPRTase. We propose a detailed chemical mechanism which is consistent with these results.
