Stoichiometry of electrocatalytic cycle of cytochrome P450 2B4

Stoichiometry of the electrocatalytical cycle of cytochrome P450 2B4 was studied in kinetic mode according to bielectrode scheme. Graphite screen-printed electrodes with immobilized cytochrome P450 2B4 were used as the operating electrode (at the potential E0′ = −450 mV) and electrodes, modified with cytochrome c (E0′ = −50 mV) or Prussian Blue (E0′ = 0), as measuring electrodes (for H2O2) and Clark-type electrode (for O2). Benzphetamine N-demethylation rate was 17 ± 3 nmol/nmol of enzyme/min, peroxide production was 4.8 ± 0.7 nmol/nmol of enzyme/min (substrate-free system), 3.3 ± 0.6 nmol/nmol of enzyme/min (0.5 mM benzphetamine), the oxygen consumption rate by Р450 2В4 was 19.4 ± 0.6 nmol/nmol of enzyme/min (in the presence of benzphetamine), 4.8 ± 0.4 nmol/nmol of enzyme/min (without substrate). Based on stoichiometry of P450 electrocatalysis adequacy of electrochemical reduction and P450-monooxygenase system was revealed.