Tsuruoka Nozomu, Sadakane Takuya, Hayashi Rika, Tsujimura Seiya
Division of Materials Science, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan.
Int J Mol Sci. 2017 Mar 10;18(3):604. doi: 10.3390/ijms18030604.
The flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH) from species require suitable redox mediators to transfer electrons from the enzyme to the electrode surface for the application of bioelectrical devices. Although several mediators for FAD-GDH are already in use, they are still far from optimum in view of potential, kinetics, sustainability, and cost-effectiveness. Herein, we investigated the efficiency of various phenothiazines and quinones in the electrochemical oxidation of FAD-GDH from . At pH 7.0, the logarithm of the bimolecular oxidation rate constants appeared to depend on the redox potentials of all the mediators tested. Notably, the rate constant of each molecule for FAD-GDH was approximately 2.5 orders of magnitude higher than that for glucose oxidase from sp. The results suggest that the electron transfer kinetics is mainly determined by the formal potential of the mediator, the driving force of electron transfer, and the electron transfer distance between the redox active site of the mediator and the FAD, affected by the steric or chemical interactions. Higher ₂ values were found for ortho-quinones than for para-quinones in the reactions with FAD-GDH and glucose oxidase, which was likely due to less steric hindrance in the active site in the case of the ortho-quinones.
来自某物种的黄素腺嘌呤二核苷酸依赖性葡萄糖脱氢酶（FAD-GDH）在生物电气设备的应用中需要合适的氧化还原介质将电子从酶转移到电极表面。尽管已经有几种用于FAD-GDH的介质在使用，但从电位、动力学、可持续性和成本效益来看，它们仍远未达到最佳状态。在此，我们研究了各种吩噻嗪和醌类在来自某物种的FAD-GDH电化学氧化中的效率。在pH 7.0时，双分子氧化速率常数的对数似乎取决于所有测试介质的氧化还原电位。值得注意的是，每个分子对FAD-GDH的速率常数比来自某物种的葡萄糖氧化酶的速率常数高约2.5个数量级。结果表明，电子转移动力学主要由介质的形式电位、电子转移驱动力以及介质的氧化还原活性位点与FAD之间的电子转移距离决定，这些受到空间或化学相互作用的影响。在与FAD-GDH和葡萄糖氧化酶的反应中，邻醌的二阶速率常数高于对醌，这可能是由于邻醌情况下活性位点的空间位阻较小。
