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.