Role of a non-ionic surfactant in direct electron transfer-type bioelectrocatalysis by fructose dehydrogenase
Role of a non-ionic surfactant in direct electron transfer-type bioelectrocatalysis by fructose dehydrogenase
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DOI：
10.1016/j.electacta.2014.11.113
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发表时间：
2015-01-10
影响因子：
6.6
通讯作者：
Kano, Kenji
中科院分区：
文献类型：
--
作者：
Kawai, Shota;Yakushi, Toshiharu;Kano, Kenji
葡萄糖氧化酶NBRC 3260的异源三聚体膜结合果糖脱氢酶（FDH）是一种直接电子转移（DET）型氧化还原酶，其亚基I含有FAD，亚基II含有3个血红素C部分作为氧化还原中心。在亲水性巯基乙醇（MEtOH）修饰的Au电极上，FDH催化果糖氧化的电流密度远大于疏水性巯基乙烷（MEtn）修饰的Au电极。添加非离子表面活性剂Triton（R）X-100（1%）完全淬灭MEtn修饰的Au电极处的催化电流，而在MEtOH修饰的Au电极处仅观察到小的竞争效应。石英晶体微量天平测量支持FDH和Triton（R）X-100在两种修饰电极上的吸附。我们提出了一个模型来解释这种现象如下。表面活性剂在具有强疏水相互作用的MEtn修饰电极上形成单分子膜，FDH吸附在表面活性剂单分子膜的表面。单分子层抑制了电子从FDH向电极的转移。另一方面，表面活性剂在亲水性MEtOH修饰电极上形成双层。表面活性剂双层和亲水电极之间的相互作用相对较弱，使得FDH取代表面活性剂并嵌入双层中以与亲水电极电化学连通。(C)2014爱思唯尔有限公司版权所有。
A heterotrimeric membrane-bound fructose dehydrogenase (FDH) from Gluconobacter japonicus NBRC3260 contains FAD in subunit I and three heme C moieties in subunit II as the redox centers, and is one of the direct electron transfer (DET)-type redox enzymes. FDH-catalyzed current density of fructose oxidation at hydrophilic mercaptoethanol (MEtOH)-modified Au electrode is much larger than that at hydrophobic mercaptoethane (MEtn)-modified Au electrode. Addition of a non-ionic surfactant Triton (R) X-100 (1%) completely quenches the catalytic current at the MEtn-modified Au electrode, while only small competitive effect is observed at the MEtOH-modified Au electrode. Quartz crystal microbalance measurements support the adsorption of FDH and Triton (R) X-100 on both of the modified electrodes. We propose a model to explain the phenomenon as follows. The surfactant forms a monolayer on the hydrophobic MEtn-modified electrode with strong hydrophobic interaction, and FDH adsorbs on the surface of the surfactant monolayer. The monolayer inhibits the electron transfer from FDH to the electrode. On the other hand, the surfactant forms a bilayer on the hydrophilic MEtOH-modified electrode. The interaction between the surfactant bilayer and the hydrophilic electrode is relatively weak so that FDH replaces the surfactant and is embedded in the bilayer to communicate electrochemically with the hydrophilic electrode. (C) 2014 Elsevier Ltd. All rights reserved.