Epoxidation of styrene by human cyt P450 1A2 by thin film electrolysis and peroxide activation compared to solution reactions

Films of human cytochrome P450 1A2 (cyt P450 1A2) and polystyrene sulfonate were constructed on carbon cloth electrodes using layer-by-layer alternate absorption and evaluated for electrochemical- and H2O2-driven enzyme-catalyzed oxidation of styrene to styrene oxide. At −0.6 V vs. saturated calomel reference electrode in an electrochemical cell, epoxidation of styrene was mediated by initial catalytic reduction of dioxygen to H2O2 which activates the enzyme for the catalytic oxidation. Slightly larger turnover rates for cyt P450 1A2 were found for the electrolytic and H2O2 (10 mM) driven reactions compared to conventional enzymatic reactions using cyt P450s, reductases, and electron donors for cytochromes P450 1A2. Cyt P450cam gave comparable turnover rates in film electrolysis and solution reactions. Results demonstrate that cyt P450 1A2 catalyzes styrene epoxidation faster than cyt P450cam, and suggests the usefulness of this thin-film electrolytic method for relative turnover rate studies of cyt P450s.