Redox-triggered events in cytochrome c nitrite reductase

• Published in: Bioelectrochemistry (Amsterdam, Netherlands) Vol. 63; no. 1; pp. 43 - 47
• Main Authors: Gwyer, James D., Angove, Hayley C., Richardson, David J., Butt, Julea N.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.06.2004
• Subjects: Coated Materials, Biocompatible - analysis; Coated Materials, Biocompatible - chemistry; Cyanide; Cyanides - chemistry; Cytochrome; Cytochromes a1 - analysis; Cytochromes a1 - antagonists & inhibitors; Cytochromes a1 - chemistry; Cytochromes c1 - analysis; Cytochromes c1 - antagonists & inhibitors; Cytochromes c1 - chemistry; Electrochemistry; Electrochemistry - methods; Enzyme Activation; Enzyme Inhibitors - chemistry; Enzyme Stability; Enzymes, Immobilized - analysis; Enzymes, Immobilized - antagonists & inhibitors; Enzymes, Immobilized - chemistry; Escherichia coli - enzymology; Heme - chemistry; Hydroxylamine - chemistry; Nitrate Reductases - analysis; Nitrate Reductases - antagonists & inhibitors; Nitrate Reductases - chemistry; Nitrite reductase; Nitrites - chemistry; Oxidation-Reduction; Substrate Specificity; Voltammetry; Cytochrome; Electrochemistry; Cyanide; Voltammetry; Nitrite reductase
• ISSN: 1567-5394; 1878-562X
• DOI: 10.1016/j.bioelechem.2003.10.013

Escherichia coli cytochrome c nitrite reductase is a homodimeric enzyme whose 10 heme centres range in reduction potential from ca. −30 to −320 mV. Protein film voltammetry (PFV) was performed to assess how the reactivity of the enzyme towards a number of small molecules was influenced by heme oxidation state. The experimental approach provided a high-resolution description of activity across the electrochemical potential domain by virtue of the fact that the enzyme sample was under the precise potential control of an electrode at all times. The current potential profiles displayed by nitrite reductase revealed that heme oxidation state has a profound, and often unanticipated, effect on the interactions with substrate molecules, nitrite and hydroxylamine, as well as the inhibitor, cyanide. Thus, PFV provides a powerful route to define redox-triggered events in this complex multi-centred redox enzyme.