E Ferapontova Elena, Gorton Lo
Group of Bioinformatics, Weblab, IT Centre, Voskhod 26a, Novosibirsk 630102, Russia.
Bioelectrochemistry. 2005 Apr;66(1-2):55-63. doi: 10.1016/j.bioelechem.2004.04.004.
Direct electrochemistry of heme multicofactor-containing enzymes, e.g., microbial theophylline oxidase (ThOx) and D-fructose dehydrogenase (FDH) from Gluconobacter industrius was studied on alkanethiol-modified gold electrodes and was compared with that of some previously studied complex heme enzymes, specifically, cellobiose dehydrogenase (CDH) and sulphite oxidase (SOx). The formal redox potentials for enzymes in direct electronic communication varied for ThOx from -112 to -101 mV (vs. Ag|AgCl), at pH 7.0, and for FDH from -158 to -89 mV, at pH 5.0 and pH 4.0, respectively, on differently charged alkanethiol layers. Direct and mediated by cytochrome c electrochemistry of FDH correlated with the existence of two active centres in the protein structure, i.e., the heme and the pyrroloquinoline quinone (PQQ) prosthetic groups. The effect of the alkanethiols of different polarity and charge on the surface properties of the gold electrodes necessary for adsorption and orientation of ThOx, FDH, CDH and SOx, favourable for the efficient electrode-enzyme electron transfer reaction, is discussed.
在烷硫醇修饰的金电极上研究了含血红素多辅因子的酶，例如微生物茶碱氧化酶（ThOx）和来自产碱葡萄糖杆菌的D-果糖脱氢酶（FDH）的直接电化学，并将其与一些先前研究过的复合血红素酶，特别是纤维二糖脱氢酶（CDH）和亚硫酸盐氧化酶（SOx）的直接电化学进行了比较。在不同电荷的烷硫醇层上，pH值为7.0时，ThOx的直接电子通讯中酶的形式氧化还原电位在-112至-101 mV（相对于Ag|AgCl）之间变化；pH值分别为5.0和4.0时，FDH的形式氧化还原电位在-158至-89 mV之间变化。FDH的直接电化学和由细胞色素c介导的电化学与蛋白质结构中两个活性中心的存在相关，即血红素和吡咯喹啉醌（PQQ）辅基。讨论了不同极性和电荷的烷硫醇对金电极表面性质的影响，这些性质对于ThOx、FDH、CDH和SOx的吸附和取向是必要的，有利于高效的电极-酶电子转移反应。
