Zhe Zhang, Alaa-Eldin F. Nassar, Zhongqing Lu, John B. Schenkman and James F. Rusling
Direct, reversible, electron transfer has been demonstrated between electrodes and native cytochrome P450cam (cyt P450cam) in lipid films. Electron injection directly from electrodes into the haem FeIII of cyt P450cam has been confirmed by the influence of the known reaction of cyt P450camFeII 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 P450FeIII and cyt P450FeII–O2 during catalytic oxidations. Cyt P450cam 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.