甲酸脱氢酶的钼和钨位点——通过扩展X射线吸收精细结构（EXAFS）观察结构差异

Formate dehydrogenase molybdenum and tungsten sites--observation by EXAFS of structural differences.

作者信息

Cramer S P, Liu C L, Mortenson L E, Spence J T, Liu S M, Yamamoto I, Ljungdahl L G

出版信息

J Inorg Biochem. 1985 Feb;23(2):119-24. doi: 10.1016/0162-0134(85)83015-4.

Abstract

Preliminary EXAFS data has been collected on the molybdenum (K-edge) in C. pasteurianum formate dehydrogenase and the tungsten (LIII-edge) in C. thermoaceticum formate dehydrogenase. In the presence of dithionite, the tungsten enzyme was devoid of W = O bonds, and exhibited average W-(O, N) and W-S bond lengths of 2.13 +/- 0.03 A and 2.39 +/- 0.03 A, respectively. In sharp contrast, the C. pasteurianum molybdenum site has three Mo = O bonds with an average bond length of 1.74 +/- 0.03 A. It is also the first molybdenum enzyme found lacking Mo-S bonds, and does not appear to be redox active in the presence of formate or dithionite. Model compounds WO2(8-hydroxyquinoline)2 = WO2(ox)2, and WO2(8 mercaptoquinoline)2 = WO2(tox)2, were also examined. Respective predicted bond lengths for WO2(ox)2 and WO2(tox)2 were W = O of 1.71, 1.73 A; W-N of 2.31, 2.29 A; W-O or W-S of 1.92 or 2.40 A, with estimated uncertainties of +/- 0.03 A.

摘要

已收集了巴氏梭菌甲酸脱氢酶中钼（K 边）和热醋梭菌甲酸脱氢酶中钨（LIII 边）的初步扩展 X 射线吸收精细结构（EXAFS）数据。在连二亚硫酸盐存在下，钨酶没有 W=O 键，其平均 W-(O,N)键长和 W-S 键长分别为 2.13±0.03 Å 和 2.39±0.03 Å。形成鲜明对比的是，巴氏梭菌的钼位点有三个 Mo=O 键，平均键长为 1.74±0.03 Å。它也是首个被发现缺乏 Mo-S 键的钼酶，在甲酸盐或连二亚硫酸盐存在下似乎没有氧化还原活性。还研究了模型化合物 WO2(8-羟基喹啉)2 = WO2(ox)2 和 WO2(8-巯基喹啉)2 = WO2(tox)2。WO2(ox)2 和 WO2(tox)2 的各自预测键长为：W=O 为 1.71、1.73 Å；W-N 为 2.31、2.29 Å；W-O 或 W-S 为 1.92 或 2.40 Å，估计不确定度为±0.03 Å。