Direct Electrochemistry of Immobilized Human Cytochrome P450 2E1

Abstract

This communication reports the first electrochemical study of the human P450 2E1 either absorbed or covalently linked to different electrode surfaces. Glassy-carbon and gold electrodes gave reversible electrochemical signals of an active P450 2E1. Molecular modeling of the enzyme helped to rationalize the results. A monolayer coverage was obtained on gold modified with cystamine/maleimide that covalently linked surface accessible cysteines of P450 2E1. The midpoint potential measured for the oriented P450 2E1 was -177 +/- 5 mV comparable to that of the FeIII/FeII of other P450 enzymes. The observed electron-transfer rate for this electrode was 10 s-1. The turnover of the active enzyme was measured with the P450 2E1 specific substrate p-nitrophenol, resulting in a KM of 130 +/- 3 muM and the formation of 2.2 muM of the p-nitrocatechol product upon application of a -300 mV bias.