Direct electron injection from electrodes to cytochrome P450cam in biomembrane-like films

Abstract

Direct, reversible, electron transfer has been demonstrated between electrodes and native cytochrome P450 _cam (cyt P450 _cam ) in lipid films. Electron injection directly from electrodes into the haem Fe ^III of cyt P450 _cam has been confirmed by the influence of the known reaction of cyt P450 _cam Fe ^II with CO on the voltammetric midpoint potential. Analysis of square wave voltammograms suggested a distribution of enzyme formal potentials in the films. With oxygen present, more than one electron was injected into the enzyme in films, mimicking in vivo electron acceptance by cyt P450Fe ^III and cyt P450Fe ^II –O ₂ during catalytic oxidations. Cyt P450 _cam films also catalysed electrochemically driven reduction of trichloroacetic acid in anaerobic solutions. These stable enzyme–lipid films may find applications in fundamental biochemical and toxicity studies, biocatalysis and biosensors.