Electrochemically driven catalysis of Rhizobium sp. NT-26 arsenite oxidase with its native electron acceptor cytochrome c₅₅₂

详细信息    查看全文

• 作者：Palraj Kalimuthu ; Matthew D. Heath ; Joanne M. Santini ; Ulrike Kappler ; Paul V. Bernhardt
• 关键词：Molybdenum ; Enzyme ; Voltammetry ; Arsenite ; Cytochrome
• 刊名：Biochimica et Biophysica Acta (BBA)/Bioenergetics
• 出版年：January, 2014
• 年：2014
• 卷：1837
• 期：1
• 页码：112-120
• 全文大小：1454 K

文摘

We describe the catalytic voltammograms of the periplasmic arsenite oxidase (Aio) from the chemolithoautotrophic bacterium Rhizobium sp. str. NT-26 that oxidizes arsenite to arsenate. Electrochemistry of the enzyme was accomplished using its native electron transfer partner, cytochrome c₅₅₂ (cyt c₅₅₂), as a mediator. The protein cyt c₅₅₂ adsorbed on a mercaptoundecanoic acid (MUA) modified Au electrode exhibited a stable, reversible one-electron voltammetric response at + 275 mV vs NHE (pH 6). In the presence of arsenite and Aio the voltammetry of cyt c₅₅₂ is transformed from a transient response to an amplified sigmoidal (steady state) wave consistent with an electro-catalytic system. Digital simulation was performed using a single set of parameters for all catalytic voltammetries obtained at different sweep rates and various substrate concentrations. The obtained kinetic constants from digital simulation provide new insight into the kinetics of the NT-26 Aio catalytic mechanism.