A decahaem cytochrome as an electron conduit in protein–enzyme redox processes

Lee, Chong; Reuillard, Bertrand; Sokol, Katarzyna P.; Laftsoglou, Theodoros; Lockwood, Colin W. J.; Rowe, Sam F.; Hwang, Ee Taek; Jeuken, Lars J. C.; Butt, Julea N.; Reisner, Erwin

doi:10.1039/c6cc02721k

Cited by 16 publications

(18 citation statements)

References 31 publications

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“…Protein film voltammetry (PFV) scans of mesoITO|MtrC recorded at different scan rates show a broad and reversible redox wave at E 1/2 = −0.21 V (all redox potentials quoted vs SHE), characteristic of the ten successive Fe III /Fe II redox couples of the hemes within MtrC ( Figure 2 a). 20 The peak currents show a linear dependence with scan rate confirming the immobilization of the protein ( Figure S2 ). Integration of the Fe II →Fe III oxidation wave allowed calculation of the charge per geometrical surface area yielding 1.9 nmol heme per cm 2 , corresponding to 0.19 nmol MtrC per cm 2 .…”

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confidence: 52%

“…At more negative potentials new signals at 419, 524, and 552 nm appeared, corresponding to the formation of the reduced Fe II -hemes in MtrC. 20 The disappearance of Fe III -heme bands at E < −0.35 V indicates that the majority of heme cofactors in the adsorbed MtrC are in electronic communication with the ITO via direct electron transfer (DET) or a combination of inter- and intramolecular electron transfer events.…”

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confidence: 99%

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High Performance Reduction of H₂O₂ with an Electron Transport Decaheme Cytochrome on a Porous ITO Electrode

Reuillard

Hildebrandt

et al. 2017

J. Am. Chem. Soc.

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The decaheme cytochrome MtrC from Shewanella oneidensis MR-1 immobilized on an ITO electrode displays unprecedented H2O2 reduction activity. Although MtrC showed lower peroxidase activity in solution compared to horseradish peroxidase, the ten heme cofactors enable excellent electronic communication and a superior activity on the electrode surface. A hierarchical ITO electrode enabled optimal immobilization of MtrC and a high current density of 1 mA cm–2 at 0.4 V vs SHE could be obtained at pH 6.5 (Eonset = 0.72 V). UV–visible and Resonance Raman spectroelectrochemical studies suggest the formation of a high valent iron-oxo species as the catalytic intermediate. Our findings demonstrate the potential of multiheme cytochromes to catalyze technologically relevant reactions and establish MtrC as a new benchmark in biotechnological H2O2 reduction with scope for applications in fuel cells and biosensors.

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High Performance Reduction of H₂O₂ with an Electron Transport Decaheme Cytochrome on a Porous ITO Electrode

Reuillard

Hildebrandt

et al. 2017

J. Am. Chem. Soc.

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“…7d). 104,111,116,117 The meso-ITO afforded a PSII loading of 19 pmol cm À2 , which resulted in a DET photocurrent of 1.6 mA cm À2 and a mediated photocurrent of 22 mA cm À2 . 104 The surface chemistry of ITO can be modified to covalently bind PSII in favour of an electroactive orientation.…”

Section: Water Oxidationmentioning

confidence: 99%

Semi-biological approaches to solar-to-chemical conversion

2020

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“…The isolated electron conduit decaheme protein MtrC was also adsorbed on mesoporous ITO electrodes and monitored using UV–vis spectro-electrochemistry to determine the redox potentials of the heme cofactors by recording changes in their oxidation state-dependent absorption. 46,47…”

Section: Uv–vis Absorption Spectroscopymentioning

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Advancing Techniques for Investigating the Enzyme–Electrode Interface

Kornienko

Robinson

et al. 2019

Acc. Chem. Res.

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ConspectusEnzymes are the essential catalytic components of biology and adsorbing redox-active enzymes on electrode surfaces enables the direct probing of their function. Through standard electrochemical measurements, catalytic activity, reversibility and stability, potentials of redox-active cofactors, and interfacial electron transfer rates can be readily measured. Mechanistic investigations on the high electrocatalytic rates and selectivity of enzymes may yield inspiration for the design of synthetic molecular and heterogeneous electrocatalysts. Electrochemical investigations of enzymes also aid in our understanding of their activity within their biological environment and why they evolved in their present structure and function. However, the conventional array of electrochemical techniques (e.g., voltammetry and chronoamperometry) alone offers a limited picture of the enzyme–electrode interface.How many enzymes are loaded onto an electrode? In which orientation(s) are they bound? What fraction is active, and are single or multilayers formed? Does this static picture change over time, applied voltage, or chemical environment? How does charge transfer through various intraprotein cofactors contribute to the overall performance and catalytic bias? What is the distribution of individual enzyme activities within an ensemble of active protein films? These are central questions for the understanding of the enzyme–electrode interface, and a multidisciplinary approach is required to deliver insightful answers.Complementing standard electrochemical experiments with an orthogonal set of techniques has recently allowed to provide a more complete picture of enzyme–electrode systems. Within this framework, we first discuss a brief history of achievements and challenges in enzyme electrochemistry. We subsequently describe how the aforementioned challenges can be overcome by applying advanced electrochemical techniques, quartz-crystal microbalance measurements, and spectroscopic, namely, resonance Raman and infrared, analysis. For example, rotating ring disk electrochemistry permits the simultaneous determination of reaction kinetics and quantification of generated products. In addition, recording changes in frequency and dissipation in a quartz crystal microbalance allows to shed light into enzyme loading, relative orientation, clustering, and denaturation at the electrode surface. Resonance Raman spectroscopy yields information on ligation and redox state of enzyme cofactors, whereas infrared spectroscopy provides insights into active site states and the protein secondary and tertiary structure. The development of these emerging methods for the analysis of the enzyme–electrode interface is the primary focus of this Account. We also take a critical look at the remaining gaps in our understanding and challenges lying ahead toward attaining a complete mechanistic picture of the enzyme–electrode interface.

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A decahaem cytochrome as an electron conduit in protein–enzyme redox processes

Cited by 16 publications

References 31 publications

High Performance Reduction of H₂O₂ with an Electron Transport Decaheme Cytochrome on a Porous ITO Electrode

High Performance Reduction of H₂O₂ with an Electron Transport Decaheme Cytochrome on a Porous ITO Electrode

Semi-biological approaches to solar-to-chemical conversion

Advancing Techniques for Investigating the Enzyme–Electrode Interface

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A decahaem cytochrome as an electron conduit in protein–enzyme redox processes

Cited by 16 publications

References 31 publications

High Performance Reduction of H2O2 with an Electron Transport Decaheme Cytochrome on a Porous ITO Electrode

High Performance Reduction of H2O2 with an Electron Transport Decaheme Cytochrome on a Porous ITO Electrode

Semi-biological approaches to solar-to-chemical conversion

Advancing Techniques for Investigating the Enzyme–Electrode Interface

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Product

Resources

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High Performance Reduction of H₂O₂ with an Electron Transport Decaheme Cytochrome on a Porous ITO Electrode

High Performance Reduction of H₂O₂ with an Electron Transport Decaheme Cytochrome on a Porous ITO Electrode