Electrostatic interaction between an enzyme and electrodes in the electric double layer examined in a view of direct electron transfer-type bioelectrocatalysis.
Electrostatic interaction between an enzyme and electrodes in the electric double layer examined in a view of direct electron transfer-type bioelectrocatalysis.
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DOI：
10.1016/j.bios.2014.07.025
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发表时间：
2015-01
影响因子：
12.6
通讯作者：
Yu Sugimoto;Y. Kitazumi;S. Tsujimura;O. Shirai;Masahiro Yamamoto;K. Kano
中科院分区：
文献类型：
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作者：
Yu Sugimoto;Y. Kitazumi;S. Tsujimura;O. Shirai;Masahiro Yamamoto;K. Kano
以铜外排氧化酶(CueO)为模型酶，通过监测氧还原的直接电子转移(DET)型生物电催化，考察了电极电位对吸附酶活力的影响。CueO吸附在裸金电极上的零电荷点(Epzc)附近显示出最高的DET活性，随着吸附电位(Ead；酶的吸附电位)远离Epzc，CueO的DET活性降低。我们提出了一个模型来解释双电层中酶与电极之间的静电相互作用影响吸附酶的取向和稳定性的现象。丁硫醇在Au电极上的自组装单分子膜降低了内亥姆霍兹平面外的电场，大大降低了CueO的DET活性的依赖性。当CueO在开路电位下吸附在裸金电极上，然后保持在比Epzc更正的保持电位(Eho)时，CueO的DET活性随着保持时间的延长而迅速下降。金属电极(σM)表面电荷密度为正的强电场导致吸附的CuEO发生致命的变性。这种变性效应在Eho<；<；Epzc上不是很严重，但负σ的电场在吸附过程中导致了一个不利于DET反应的取向。带正电荷的新霉素对吸附在Ead<；<；Epzc上的CueO有促进作用。该模型还对这一现象进行了解释。
Effects of the electrode poential on the activity of an adsorbed enzyme has been examined by using copper efflux oxidase (CueO) as a model enzyme and by monitoring direct electron transfer (DET)-type bioelectrocatalysis of oxygen reduction. CueO adsorbed on bare Au electrodes at around the point of zero charge (Epzc) shows the highest DET activity, and the activity decreases as the adsorption potential (Ead; at which the enzyme adsorbs) is far fromEpzc. We propose a model to explain the phenomena in which the electrostatic interaction between the enzyme and electrodes in the electric double layer affects the orientation and the stability of the adsorbed enzyme. The self-assembled monolayer of butanethiol on Au electrodes decreases the electric field in the outside of the inner Helmholtz plane and drastically diminishes theEaddependence of the DET activity of CueO. When CueO is adsorbed on bare Au electrodes under open circuit potential and then is held at hold potentials (Eho) more positive thanEpzc, the DET activity of the CueO rapidly decreases with the hold time. The strong electric field with positive surface charge density on the metallic electrode (σM) leads to fatal denaturation of the adsorbed CueO. Such denaturation effect is not so serious atEho<<Epzc, but the electric field with negativeσMinduces an orientation inconvenient for the DET reaction during the adsorption process. A positively charged neomycin shows a promoter ability to CueO adsorbed atEad<<Epzc. The phenomenon is also explained on the proposed model.