School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane 4072, Australia.
Department of Biochemistry, University of California Riverside, 900 University Avenue, Riverside, California 92521, United States.
J Phys Chem B. 2023 Oct 5;127(39):8382-8392. doi: 10.1021/acs.jpcb.3c04652. Epub 2023 Sep 20.
The bacterial molybdenum (Mo)-containing formate dehydrogenase (FdsDABG) from is a soluble NAD-dependent enzyme belonging to the DMSO reductase family. The holoenzyme is complex and possesses nine redox-active cofactors including a bis(molybdopterin guanine dinucleotide) (bis-MGD) active site, seven iron-sulfur clusters, and 1 equiv of flavin mononucleotide (FMN). FdsDABG catalyzes the two-electron oxidation of HCOO (formate) to CO and reversibly reduces CO to HCOO under physiological conditions close to its thermodynamic redox potential. Here we develop an electrocatalytically active formate oxidation/CO reduction system by immobilizing FdsDABG on a glassy carbon electrode in the presence of coadsorbents such as chitosan and glutaraldehyde. The reversible enzymatic interconversion between HCOO and CO by FdsDABG has been realized with cyclic voltammetry using a range of artificial electron transfer mediators, with methylene blue (MB) and phenazine methosulfate (PMS) being particularly effective as electron acceptors for FdsDABG in formate oxidation. Methyl viologen (MV) acts as both an electron acceptor (MV) in formate oxidation and an electron donor (MV) for CO reduction. The catalytic voltammetry was reproduced by electrochemical simulation across a range of sweep rates and concentrations of formate and mediators to provide new insights into the kinetics of the FdsDABG catalytic mechanism.
来自 的细菌钼（Mo）结合的甲酸盐脱氢酶（FdsDABG）是一种可溶性 NAD 依赖性酶，属于 DMSO 还原酶家族。全酶结构复杂，包含九个氧化还原活性辅因子，包括双（钼喋呤鸟嘌呤二核苷酸）（bis-MGD）活性位点、七个铁硫簇和 1 当量黄素单核苷酸（FMN）。FdsDABG 在接近其热力学氧化还原电势的生理条件下，催化 HCOO（甲酸盐）的两电子氧化为 CO，并可逆地将 CO 还原为 HCOO。在这里，我们通过在存在壳聚糖和戊二醛等共吸附剂的情况下将 FdsDABG 固定在玻碳电极上来开发一种电催化活性的甲酸盐氧化/CO 还原系统。通过使用一系列人工电子转移介体的循环伏安法，实现了 FdsDABG 介导的 HCOO 和 CO 之间的可逆酶促相互转化，其中亚甲基蓝（MB）和吩嗪甲硫酸盐（PMS）作为 FdsDABG 在甲酸盐氧化中的电子受体特别有效。甲紫（MV）既可以作为甲酸盐氧化的电子受体（MV），也可以作为 CO 还原的电子供体（MV）。通过在一系列甲酸盐和介体的扫速和浓度范围内进行电化学模拟，重现了催化伏安法，为 FdsDABG 催化机制的动力学提供了新的见解。
