[Photoreduction of flavocytochrome P450 2B4]

It was shown that noncovalent complexes of riboflavins and cytochrome P450 2B4 (flavocytochrome P450 2B4) can be used for photoinduced intramolecular electron transfer between the isoalloxazine cycle of flavins and the cytochrome P450 2B4 heme. The measurement of the photocurrent generated by photoreduction of noncovalent flavocytochrome P450 2B4 was carried out. It was found that, in the presence of typical substrates for cytochromes P450, the cathode photocurrent generated by both riboflavin and a mixture of riboflavin with cytochrome P450 decreases. A comparison of photocurrents in the presence and absence of substrates enabled one to register xenobiotics in solutions and use the photosensitivity of artificial flavocytochrome P450 for the determination of xenobiotic concentration. It was demonstrated that artificial flavocytochromes may serve as molecular amplifiers of the photocurrent generated upon the reduction of flavins. The introduction of flavin residues into the cytochrome P450 molecule transformed this hemoprotein into a photoreceptor and a photodiod and, in addition, into a photoactivated enzyme.