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The steady-state kinetics of oxidation of rat liver NADPH: cytochrome P450 reductase (EC 1.6.2.4) by quinones, aromatic nitrocompounds, ferricyanide, Fe(EDTA)-, and cytochrome c has been studied. The logarithms of bimolecular rate constants of reduction (kcat/Km) of quinones and nitrocompounds increase with the increase in their single-electronreduction potential (E1(7)), reaching a maximum value at E1(7) > -0.15 V. The reactivities of nitroaromatics are about by an order of magnitude lower than the reactivities of quinones. For a series of nitroaromatics including the compounds with previously undetermined E1(7) values, an orthogonality was found between their reactivities toward cytochrome P450 reductase, flavocytochrome b2 (EC 1.1.2.3), and the NADPH: adrenodoxin reductase (EC 1.18.1.2)-adrenodoxin system. This indicates the absence of significant specific interactions during these reactions. The effects of ionic strength on reaction kinetics and the character of inhibition by a product of reaction, NADP+, are in accordance with the reduction of oxidants at the negatively charged site in the surroundings of FMN of P450 reductase. Quinones inactivate oxidized reductase modifying the NADP(H) binding site. The redox cycling of quinones markedly slows the inactivation. The kinetic data presented are consistent with an outer-sphere electron transfer mechanism. The analysis of kinetics of reduction of cytochrome c, ferricyanide, and Fe(EDTA)- using the model of Mauk et al. (A. G. Mauk, R. A. Scott, and H. B. Gray (1980) J. Am. Chem. Soc. 102, 4360-4363) gives calculated distances of FMN from the surface of protein globule, 0.33-0.63 nm. The data from nitroreductase reactions of cytochrome P450 reductase, flavocytochrome b2, and adrenodoxin were used for approximate evaluation of previously unknown E1(7) of nitrocompounds.
N Cénas, and
Z Anusevicius, and
D Bironaité, and
G I Bachmanova, and
A I Archakov, and
K Ollinger
December 2010,
The Biochemical journal,
N Cénas, and
Z Anusevicius, and
D Bironaité, and
G I Bachmanova, and
A I Archakov, and
K Ollinger
February 2008,
The Journal of biological chemistry,
N Cénas, and
Z Anusevicius, and
D Bironaité, and
G I Bachmanova, and
A I Archakov, and
K Ollinger
July 1992,
The Journal of biological chemistry,
N Cénas, and
Z Anusevicius, and
D Bironaité, and
G I Bachmanova, and
A I Archakov, and
K Ollinger
February 1976,
Archives of biochemistry and biophysics,
N Cénas, and
Z Anusevicius, and
D Bironaité, and
G I Bachmanova, and
A I Archakov, and
K Ollinger
June 2003,
Biochemical Society transactions,
N Cénas, and
Z Anusevicius, and
D Bironaité, and
G I Bachmanova, and
A I Archakov, and
K Ollinger
January 2011,
Biochimica et biophysica acta,
N Cénas, and
Z Anusevicius, and
D Bironaité, and
G I Bachmanova, and
A I Archakov, and
K Ollinger
August 2005,
Archives of biochemistry and biophysics,
N Cénas, and
Z Anusevicius, and
D Bironaité, and
G I Bachmanova, and
A I Archakov, and
K Ollinger
January 2009,
Nature protocols,
N Cénas, and
Z Anusevicius, and
D Bironaité, and
G I Bachmanova, and
A I Archakov, and
K Ollinger
November 1993,
Biochemistry,
N Cénas, and
Z Anusevicius, and
D Bironaité, and
G I Bachmanova, and
A I Archakov, and
K Ollinger
January 2009,
Postepy biochemii,
