STAFF PRIORITY TIME XAS OF DESULFOVIBRIO DESULFURICANS FORMATE DEHYDROGENASE

我们研究了氧化的和 脱硫弧菌连二亚硫酸盐还原甲酸脱氢酶 使用XAS在Mo和Se K边缘处测定脱硫剂。 从 Mo（VI）的氧化态活性中心有四个Mo-S 配体（与双-喋茚二硫烯辅因子配位一致）， 具有一个Mo=O和一个Mo-Se，而还原的Mo（IV）活性位 含有四个Mo-S、一个Mo-O（-OH或-OH 2）和一个Mo-Se。 从Se 从这个角度来看，氧化蛋白除了具有硒钼和 预期为Se-C配体，键长为2.19 E的Se-S。减少 这种蛋白质Se-S不存在。 这种协调类似于 观察到E. coli甲酸脱氢酶（G. N.乔治角M. Colangelo，J. Dong，R. A.斯科特，S。V. Khangulov，V. N.格拉迪舍夫，T. C. Stadtman J.Amer.Chem.Soc.1998，接受出版）， 除了在D.脱硫酶连二亚硫酸盐可以减少 Se-S键

We have studied the active site structure of oxidized and dithionite-reduced formate dehydrogenase from Desulfovibrio desulfuricans using XAS at both the Mo and Se K-edges. From the molybdenum perspective the oxidized Mo(VI) active site has four Mo-S ligands (consitant with a bis-pterindithiolene cofactor coordination), with one Mo=O and one Mo-Se, while the reduced Mo(IV) active site contains four Mo-S, one Mo-O (-OH or -OH2) and one Mo-Se. From the Se perspective, the oxidized protein has, in addition to the Se-Mo and Se-C ligands expected, a Se-S with a bond-length of 2.19 E. In reduced protein this Se-S is not present. This coordination is similar to that observed for E. coli formate dehydrogenase (G. N. George, C. M. Colangelo, J. Dong, R. A. Scott, S. V. Khangulov, V. N. Gladyshev, T. C. Stadtman J. Amer. Chem. Soc. 1998, accepted for publication), except that in the D. desulfuricans enzyme dithionite can reduce the Se-S bond.