Vogt Stephan, Schneider Marcel, Schäfer-Eberwein Heiko, Nöll Gilbert
Nöll Junior Research Group, University of Siegen , Adolf-Reichwein-Straße 2, D-57068 Siegen, Germany.
Anal Chem. 2014 Aug 5;86(15):7530-5. doi: 10.1021/ac501289x. Epub 2014 Jul 22.
The pH dependent redox potential of the oxidoreductase glucose oxidase (GOx) from Aspergillus niger, which is the most frequently applied enzyme in electrochemical glucose biosensors and biofuel cells, was measured between pH 4.5 and 8.5 using UV/vis spectroelectrochemistry. In the entire pH range under investigation, the flavin adenine dinucleotide cofactor of GOx changed directly from the oxidized quinone to the doubly reduced hydroquinone. No stable semiquinoid species could be detected if electrochemical equilibrium was reached. From the pH dependency of the GOx redox potential, a pK(a) of 7.2 has been determined for the GOx flavohydroquinone. At pH values ≤6.0, a dependency of the reduction mechanism and the GOx redox potential on the presence of halides, especially on Cl(-), was observed. For the development of glucose biosensors and glucose biofuel cell anodes working at physiological or neutral pH, the GOx redox potentials at pH 7.4 and pH 7.0 are of main interest. Here values of E(1/2 pH 7.4) = -97 ± 3 mV and E(1/2 pH 7.0) = -80 ± 4 mV have been determined.
黑曲霉氧化还原酶葡萄糖氧化酶（GOx）的pH依赖性氧化还原电位，是电化学葡萄糖生物传感器和生物燃料电池中最常用的酶，使用紫外/可见光谱电化学在pH 4.5至8.5之间进行了测量。在整个研究的pH范围内，GOx的黄素腺嘌呤二核苷酸辅因子直接从氧化醌转变为双还原对苯二酚。如果达到电化学平衡，则无法检测到稳定的半醌类物质。根据GOx氧化还原电位的pH依赖性，已确定GOx黄素对苯二酚的pK(a)为7.2。在pH值≤6.0时，观察到还原机制和GOx氧化还原电位对卤化物存在的依赖性，尤其是对Cl(-)的依赖性。对于在生理或中性pH下工作的葡萄糖生物传感器和葡萄糖生物燃料电池阳极的开发，pH 7.4和pH 7.0时的GOx氧化还原电位是主要关注点。此处已确定E(1/2 pH 7.4) = -97 ± 3 mV和E(1/2 pH 7.0) = -80 ± 4 mV的值。
