Crystal Structures of Catalytic Intermediates of Human Selenophosphate Synthetase 1
Crystal Structures of Catalytic Intermediates of Human Selenophosphate Synthetase 1
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DOI：
10.1016/j.jmb.2009.05.032
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发表时间：
2009-07-24
影响因子：
5.6
通讯作者：
Su, Xiao-Dong
中科院分区：
文献类型：
--
作者：
Wang, Kai-Tuo;Wang, Juan;Su, Xiao-Dong
硒磷酸合成酶催化高活性硒供体分子硒磷酸盐的合成，硒磷酸盐是硒代谢的关键中间体。我们已经确定了高分辨率的晶体结构的人硒磷酸合成酶1（hSPS 1）。一个意想不到的反应中间体，与紧密结合的磷酸盐和ADP在活性位点已被捕获的结构。酶促分析显示，hSPS 1在磷酸盐存在下具有低ADP水解活性。我们的结构和酶的结果表明，消耗ATP的第二个高能磷酸酯键可以保护不稳定的产物硒磷酸在催化反应。我们解决了另一个在活性位点具有钾离子的hSPS 1结构。比较两种结构，我们能够定义的单价阳离子结合位点的酶。提出了ADP水解步骤的详细机理和一价阳离子对hSPS 1催化反应的确切作用。(C)2009爱思唯尔有限公司版权所有。
Selenophosphate synthetase catalyzes the synthesis of the highly active selenium donor molecule selenophosphate, a key intermediate in selenium metabolism. We have determined the high-resolution crystal structure of human selenophosphate synthetase 1 (hSPS1). An unexpected reaction intermediate, with a tightly bound phosphate and ADP at the active site has been captured in the structure. An enzymatic assay revealed that hSPS1 possesses low ADP hydrolysis activity in the presence of phosphate. Our structural and enzymatic results suggest that consuming the second high-energy phosphoester bond of ATP could protect the labile product selenophosphate during catalytic reaction. We solved another hSPS1 structure with potassium ions at the active sites. Comparing the two structures, we were able to define the monovalent cation-binding site of the enzyme. The detailed mechanism of the ADP hydrolysis step and the exact function of the monovalent cation for hSPS1 catalytic reaction are proposed. (C) 2009 Elsevier Ltd. All rights reserved.