Moreno C, Franco R, Moura I, Le Gall J, Moura J J
Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Portugal.
Eur J Biochem. 1993 Nov 1;217(3):981-9. doi: 10.1111/j.1432-1033.1993.tb18329.x.
The kinetics of electron transfer between the Desulfovibrio gigas hydrogenase and several electron-transfer proteins from Desulfovibrio species were investigated by cyclic voltammetry, square-wave voltammetry and chronoamperometry. The cytochrome c3 from Desulfovibrio vulgaris (Hildenborough), Desulfovibrio desulfuricans (Norway 4), Desulfovibrio desulfuricans (American Type Culture Collection 27774) and D. gigas (NCIB 9332) were used as redox carriers. They differ in their redox potentials and isoelectric point. Depending on the pH, all the reduced forms of these cytochromes were effective in electron exchange with hydrogenase. Other small electron-transfer proteins such as ferredoxin I, ferredoxin II and rubredoxin from D. gigas were tentatively used as redox carriers. Only ferredoxin II was effective in mediating electron exchange between hydrogenase and the working electrode. The second-order rate constants k for the reaction between reduced proteins and hydrogenase were calculated based on the theory of the simplest electrocatalytic mechanism [Moreno, C., Costa, C., Moura, I., Le Gall, J., Liu, M. Y., Payne, W. J., van Dijk, C. & Moura, J. J. G. (1993) Eur. J. Biochem. 212, 79-86] and the results obtained by cyclic voltammetry were compared with those obtained by chronoamperometry. Values for k of 10(5)-10(6) M-1 s-1 (cytochrome c3 as electron carrier) and 10(4) M-1 s-1 (ferredoxin II as the electron carrier) were determined. The rate-constant values are discussed in terms of the existence of an electrostatic interaction between the electrode surface and the redox carrier and between the redox carrier and a positively charged part of the enzyme.
通过循环伏安法、方波伏安法和计时电流法研究了巨大脱硫弧菌氢化酶与几种脱硫弧菌属电子传递蛋白之间的电子转移动力学。来自普通脱硫弧菌（希登伯勒）、脱硫脱硫弧菌（挪威4）、脱硫脱硫弧菌（美国典型培养物保藏中心27774）和巨大脱硫弧菌（NCIB 9332）的细胞色素c3用作氧化还原载体。它们的氧化还原电位和等电点不同。根据pH值，这些细胞色素的所有还原形式在与氢化酶的电子交换中均有效。其他小的电子传递蛋白，如巨大脱硫弧菌的铁氧化还原蛋白I、铁氧化还原蛋白II和红素氧还蛋白，被初步用作氧化还原载体。只有铁氧化还原蛋白II在介导氢化酶与工作电极之间的电子交换中有效。基于最简单的电催化机制理论[莫雷诺，C.，科斯塔，C.，莫拉，I.，勒加尔，J.，刘，M.Y.，佩恩，W.J.，范迪克，C.和莫拉，J.J.G.（1993）欧洲生物化学杂志212，79 - 86]计算了还原蛋白与氢化酶反应的二级速率常数k，并将循环伏安法得到的结果与计时电流法得到的结果进行了比较。确定了k值为10(5)-10(6) M-1 s-1（细胞色素c3作为电子载体）和10(4) M-1 s-1（铁氧化还原蛋白II作为电子载体）。根据电极表面与氧化还原载体之间以及氧化还原载体与酶的带正电部分之间存在静电相互作用来讨论速率常数的值。
