[The optical biosensor study of the redox partners interactions within the cytochrome P450 2B4-containing monooxygenase system in hydroxylation conditions].

Interactions between cytochrome P450 2B4, NADPH:cytochrome P450 reductase and cytochrome b5 have been investigated in the presence of a substrate (7-pentoxyresorufin) and an electron donor, NADPH, in the monomeric reconstituted P450 2B4-contained monooxygenase system. Each partner was immobilized via its amino groups on the carboxymethyldextran biochip surface of an optical biosensor IAsys+. It was shown that, despite immobilization of any of the partners (via their respective amino groups) onto the carboxymethyldextran surface of the IAsys+ optical biosensor, its activity didn't loss. The formation of binary d-Fp/d-2B4 complexes was registered. The association/dissociation rate constants (kon/koff) were (0,013 +/- 0,005) x 10(6) M(-1) x s(-1)/0,05 +/- 0,02 s(-1), equilibrium dissociation constant (K(D)) was (0,26 +/- 0,13) x 10(-6) M. Comparison of kon, koff and K(D) for d-Fp/d-2B4 complexes in oxidation conditions with corresponding constants for the oxidized protein forms--(0,10 +/- 0,03) x 10(6) M(-1) x s(-1)/(0,14 +/- 0,06) s(-1), (0,71 +/- 0,37) x 10(-6) M--shows that the decrease in kon and K(D) occurs due to the increase in lifetime during transition from oxidized to hydroxylation conditions. Complex formation between d-Fp and d-b5 was not registered in oxidation and hydroxylation conditions. The ternary d-Fp/d-2B4/d-b5 complexes formation was shown in hydroxylation and oxidation conditions.

[Effect of a magnetic field on the rate of H202 breakdown by catalase and by an Fe3+--EDTA complex]. / Vliianie magnitnogo polia na skorost' razlozheniia H202 katalazoi i kompleksom EDTA s Fe3+.

The acceleration of H202 decomposition induced by catalase and the dimer complex [Fe3+(EDTA)]2 has been observed in a constant magnetic field. The effect increases with the field increasing up to 8000 Oe, reaching 20 +/- 5% and 24 +/- 5% for catalase and [Fe3+(EDTA)]2 respectively. The results are discussed within the hypothesis of a one-electron reaction mechanism using the models developed specially to explain the magnetic effects in radical reactions. It is supposed that the stage which is affected by the magnetic field is the electron transfer coupled with Fe3+O./2 paramagnetic species. The interpretation proposed does not exclude an alternative possibility of the magnetic effects during the electron transfer to two iron atoms by a two-electron (synchronous) mechanism.