Food Biotechnology Laboratory, Department of Food Sciences and Technology, BOKU - University of Natural Resources and Life Sciences , Muthgasse 18, A-1190 Vienna, Austria.
Langmuir. 2012 Apr 24;28(16):6714-23. doi: 10.1021/la3005486. Epub 2012 Apr 12.
Cellobiose dehydrogenase (CDH) is capable of direct electron transfer (DET) on various carbon and thiol-modified gold electrodes. As a result, these systems have been utilized as biocatalyst in biosensors and biofuel cell anodes. Class I CDHs, from basidiomycetous fungi, are highly specific to cellulose or lactose, and DET is only observed at pH values below 5.5. To extend the applicability of CDH-based electrodes, the catalytic properties and the behavior on electrode surfaces of ascomycetous class II CDHs from Chaetomium attrobrunneum, Corynascus thermophilus, Dichomera saubinetii, Hypoxylon haematostroma, Neurospora crassa, and Stachybotrys bisbyi were investigated. We found that class II CDHs have diverse properties but generally show a lower substrate specificity than class I CDHs by converting also glucose and maltose. Intramolecular electron transfer (IET) and DET at neutral and alkaline pH were observed and elucidated by steady-state kinetics, pre-steady-state kinetics, and electrochemical measurements. The CDHs ability to interact with the electron acceptor cytochrome c and to communicate with electrode surfaces through DET at various pH conditions was used to classify the investigated enzymes. In combination with stopped-flow measurements, a model for the kinetics of the pH-dependent IET is developed. The efficient glucose turnover at neutral/alkaline pH makes some of these new CDHs potential candidates for glucose biosensors and biofuel cell anodes.
纤维二糖脱氢酶（CDH）能够在各种碳和硫醇修饰的金电极上进行直接电子转移（DET）。因此，这些系统已被用作生物传感器和生物燃料电池阳极中的生物催化剂。来自担子菌的 I 型 CDH 对纤维素或乳糖具有高度特异性，并且仅在 pH 值低于 5.5 时观察到 DET。为了扩展基于 CDH 的电极的适用性，研究了来自 Chaetomium attrobrunneum、Corynascus thermophilus、Dichomera saubinetii、Hypoxylon haematostroma、Neurospora crassa 和 Stachybotrys bisbyi 的曲霉 II 型 CDH 的催化性质和在电极表面的行为。我们发现，II 型 CDH 具有多种性质，但通常比 I 型 CDH 具有更低的底物特异性，因为它还可以转化葡萄糖和麦芽糖。通过稳态动力学、预稳态动力学和电化学测量观察到并阐明了分子内电子转移（IET）和中性及碱性 pH 下的 DET。CDH 与电子受体细胞色素 c 相互作用以及通过 DET 在各种 pH 条件下与电极表面进行通信的能力用于对研究酶进行分类。结合停流测量，开发了一个用于 pH 依赖性 IET 动力学的模型。在中性/碱性 pH 下高效的葡萄糖周转率使这些新的 CDH 中的一些成为葡萄糖生物传感器和生物燃料电池阳极的潜在候选者。
