A Thiamine-Dependent Enzyme Utilizes an Active Tetrahedral Intermediate in Vitamin K Biosynthesis
作者:Haigang Song、Chen Dong、Mingming Qin、Yaozong Chen、Yueru Sun、Jingjing Liu、Wan Chan、Zhihong Guo
DOI:10.1021/jacs.6b03437
日期:2016.6.15
reactive intermediate mediating essential thiamine-dependent catalysis in central metabolic pathways. However, this intermediate is not found in the thiamine-dependent catalysis of the vitamin K biosynthetic enzyme MenD. Instead, an active tetrahedral post-decarboxylation intermediate is stably formed in the enzyme and was structurally determined at 1.34 Å resolution in crystal. This intermediate takes
烯胺是众所周知的反应性中间体,介导中央代谢途径中必需的硫胺素依赖性催化。然而,在维生素 K 生物合成酶 MenD 的硫胺素依赖性催化中未发现该中间体。相反,活性四面体脱羧后中间体在酶中稳定形成,并在晶体中以 1.34 Å 分辨率进行结构测定。该中间体采用独特的构象,在其四面体反应中心和辅因子中氨基嘧啶部分的外环氮原子之间仅允许一个质子,距离为 3.0 Å。它很容易转化为酶促反应的最终产物,在其反应中心具有可溶剂交换的质子。