Study for structure and function of a flavoenzyme designed to a novel diagnostic enzyme

FAD依赖的D-葡萄糖脱氢酶[GDH，EC 1.1.99.10]来自A.使用FAD作为辅因子，β-葡糖苷酶催化从D-葡萄糖到D-β-l，5-内酯的反应。在氧化半反应过程中，还原的FAD被电子受体如2，6-二氯酚靛酚和对苯醌再氧化。预期GDH将用作用于监测糖尿病患者的血糖水平的生物传感器的诊断酶。另一方面，来自A. 1.1.3.4与GDH的序列同一性为29%的尼日尔催化相同的还原半反应，但不同的氧化半反应;还原的FAD被O2再氧化。GDH的氧反应性比GOX慢。为了阐明GDH的催化反应和底物结合机制以及结构特征如何支配GDH和GOX之间的氧化半反应，我们使用X射线晶体学研究了GDH。

FAD-dependent D-glucose dehydrogenase [GDH, EC 1.1.99.10] from A. oryzae catalyzes a reaction from D-glucose to D-glucono-1, 5-lactone using FAD as a cofactor. During the oxidative half-reaction, the reduced FAD is re-oxidized by electron acceptors, for instance 2, 6-dichlorophenol-indophenol and p-benzoquinone. It is expected that GDH would be utilized as a diagnostic enzyme for a biosensor that monitors the blood glucose level of diabetic patients. On the other hand, FAD-dependent D-glucose oxidase [GOX, EC 1.1.3.4] from A. niger, which shows a sequence identity of 29% with the GDH, catalyzes the same reductive half-reaction but different oxidative half-reaction; the reduced FAD is re-oxidized by O2. An oxygen reactivity of GDH is slower than that of GOX. To clarify the catalytic-reaction and substrate-binding mechanisms of GDH and how structural features govern the oxidative half-reaction between GDH and GOX, we investigated the GDH using X-ray crystallography.