Reduction and catalytic properties of cytochrome P-450 LM2 in reconstituted system containing monomeric carriers.
The membrane microsomal monooxygenase system can be reconstituted in solution from NADPH-specific flavoprotein and cytochrome P-450 which exist in the monomeric state in the presence of Emulgen 913 at molar ratio of the proteins and detergent of 1:1:300. Oxidized and dithionite-reduced monomers of cytochrome P-450 were much less thermostable than its initial aggregates, while thermal stability of NADPH-specific flavoprotein did not depend on its aggregation state. Binding spectra of cytochrome P-450 monomers with benzphetamine were atypical and had an absorbance minimum at 422 nm only. The addition of benzphetamine and/or flavoprotein to cytochrome P-450 monomers did not cause the spin equilibrium shift and the low-spin form content was higher than 85% in all cases. Investigation of the dependence of the initial rates of NADPH-dependent cytochrome P-450 reduction and benzphetamine oxidation on the stoichiometry of the flavoprotein and cytochrome P-450 at their constant total concentration showed that the molar ratio of 1:1 was required for maximal activity. Thus this system works in full accordance with the mass action law.
Kanaeva
I P
IP
Institute of Physico-Chemical Medicine, Moscow, USSR.
Skotselyas
E D
ED
Turkina
I F
IF
Petrochenko
E V
EV
Davydov
D R
DR
Kondrashin
S K
SK
Dzuzenova
Ch S
ChS
Bachmanova
G I
GI
Archakov
A I
AI
D000818:Animals; D001589:Benzphetamine / Q000378:metabolism; D002384:Catalysis; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D011817:Rabbits; D013696:Temperature
D046911:Macromolecular Substances; D001589:Benzphetamine; D009249:NADP; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases