舍瓦内拉
化学
电子顺磁共振
电子转移
希瓦氏菌属
细胞色素
电子传输链
电子受体
循环伏安法
分析化学(期刊)
光化学
电化学
电极
核磁共振
物理化学
生物化学
有机化学
细菌
酶
物理
生物
遗传学
作者
Robert S. Hartshorne,Brian N. Jepson,Thomas A. Clarke,Sarah J. Field,Jim K. Fredrickson,John M. Zachara,Liang Shi,Julea N. Butt,David J. Richardson
标识
DOI:10.1007/s00775-007-0278-y
摘要
MtrC is a decaheme c-type cytochrome associated with the outer cell membrane of Fe(III)-respiring species of the Shewanella genus. It is proposed to play a role in anaerobic respiration by mediating electron transfer to extracellular mineral oxides that can serve as terminal electron acceptors. The present work presents the first spectropotentiometric and voltammetric characterization of MtrC, using protein purified from Shewanella oneidensis MR-1. Potentiometric titrations, monitored by UV-vis absorption and electron paramagnetic resonance (EPR) spectroscopy, reveal that the hemes within MtrC titrate over a broad potential range spanning between approximately +100 and approximately -500 mV (vs. the standard hydrogen electrode). Across this potential window the UV-vis absorption spectra are characteristic of low-spin c-type hemes and the EPR spectra reveal broad, complex features that suggest the presence of magnetically spin-coupled low-spin c-hemes. Non-catalytic protein film voltammetry of MtrC demonstrates reversible electrochemistry over a potential window similar to that disclosed spectroscopically. The voltammetry also allows definition of kinetic properties of MtrC in direct electron exchange with a solid electrode surface and during reduction of a model Fe(III) substrate. Taken together, the data provide quantitative information on the potential domain in which MtrC can operate.
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