Auchère Françoise, Pauleta Sofia R, Tavares Pedro, Moura Isabel, Moura José J G
REQUIMTE-Centro de Química Fina e Biotecnologia, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516, Caparica, Portugal.
J Biol Inorg Chem. 2006 Jun;11(4):433-44. doi: 10.1007/s00775-006-0090-0. Epub 2006 Mar 17.
In this work we present a kinetic study of the superoxide-mediated electron transfer reactions between rubredoxin-type proteins and members of the three different classes of superoxide reductases (SORs). SORs from the sulfate-reducing bacteria Desulfovibrio vulgaris (Dv) and D. gigas (Dg) were chosen as prototypes of classes I and II, respectively, while SOR from the syphilis spirochete Treponema pallidum (Tp) was representative of class III. Our results show evidence for different behaviors of SORs toward electron acceptance, with a trend to specificity for the electron donor and acceptor from the same organism. Comparison of the different kapp values, 176.9+/-25.0 min(-1) in the case of the Tp/Tp electron transfer, 31.8+/-3.6 min(-1) for the Dg/Dg electron transfer, and 6.9+/-1.3 min(-1) for Dv/Dv, could suggest an adaptation of the superoxide-mediated electron transfer efficiency to various environmental conditions. We also demonstrate that, in Dg, another iron-sulfur protein, a desulforedoxin, is able to transfer electrons to SOR more efficiently than rubredoxin, with a kapp value of 108.8+/-12.0 min(-1), and was then assigned as the potential physiological electron donor in this organism.
在这项工作中，我们对红氧还蛋白型蛋白质与三类不同超氧化物还原酶（SORs）成员之间的超氧化物介导的电子转移反应进行了动力学研究。分别选择来自硫酸盐还原菌嗜脱硫弧菌（Dv）和巨大脱硫弧菌（Dg）的SOR作为I类和II类的原型，而来自梅毒螺旋体（Tp）的SOR代表III类。我们的结果显示了SORs在电子接受方面的不同行为，倾向于对来自同一生物体的电子供体和受体具有特异性。比较不同的kapp值，Tp/Tp电子转移的kapp值为176.9±25.0 min⁻¹，Dg/Dg电子转移的kapp值为31.8±3.6 min⁻¹，Dv/Dv的kapp值为6.9±1.3 min⁻¹，这可能表明超氧化物介导的电子转移效率适应了各种环境条件。我们还证明，在Dg中，另一种铁硫蛋白，即脱硫铁氧还蛋白，能够比红氧还蛋白更有效地将电子转移到SOR，其kapp值为108.8±12.0 min⁻¹，因此被确定为该生物体中潜在的生理电子供体。
