scholarly journals Reaction of Human Cytochrome P450 3A4 with Peroxynitrite: Nitrotyrosine Formation on the Proximal Side Impairs Its Interaction with NADPH-Cytochrome P450 Reductase

2012 ◽  
Vol 25 (12) ◽  
pp. 2642-2653 ◽  
Author(s):  
Hsia-lien Lin ◽  
Cesar Kenaan ◽  
Haoming Zhang ◽  
Paul F. Hollenberg
Keyword(s):  
Cytochrome P450 ◽  
Cytochrome P450 3A4 ◽  
Cytochrome P450 Reductase ◽  
Nadph Cytochrome ◽  
Proximal Side ◽  
P450 Reductase ◽  
Human Cytochrome ◽  
Nadph Cytochrome P450 Reductase

Construction ofSalmonella typhimurium YG7108 strains, each coexpressing a form of human cytochrome P450 with NADPH-cytochrome P450 reductase

2001 ◽  
Vol 38 (4) ◽  
pp. 329-338 ◽  
Author(s):  
Ken-ichi Fujita ◽  
Kazuo Nakayama ◽  
Yoshiyuki Yamazaki ◽  
Kazuhiro Tsuruma ◽  
Masami Yamada ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Cytochrome P450 Reductase ◽  
Nadph Cytochrome ◽  
P450 Reductase ◽  
Human Cytochrome ◽  
Nadph Cytochrome P450 Reductase

Kinetics of electron transfer between NADPH-cytochrome P450 reductase and cytochrome P450 3A4

2010 ◽  
Vol 432 (3) ◽  
pp. 485-494 ◽  
Author(s):  
Yassar Farooq ◽  
Gordon C. K. Roberts
Keyword(s):  
Electron Transfer ◽  
Cytochrome P450 ◽  
Hill Coefficient ◽  
Molar Ratio ◽  
Cytochrome P450 3A4 ◽  
Cytochrome P450 Reductase ◽  
Nadph Cytochrome ◽  
P450 Reductase ◽  
Absorbance Change ◽  
Nadph Cytochrome P450 Reductase

We have incorporated CYP3A4 (cytochrome P450 3A4) and CPR (NADPH-cytochrome P450 reductase) into liposomes with a high lipid/protein ratio by an improved method. In the purified proteoliposomes, CYP3A4 binds testosterone with Kd (app)=36±6 μM and Hill coefficient=1.5±0.3, and 75±4% of the CYP3A4 can be reduced by NADPH in the presence of testosterone. Transfer of the first electron from CPR to CYP3A4 was measured by stopped-flow, trapping the reduced CYP3A4 as its Fe(II)–CO complex and measuring the characteristic absorbance change. Rapid electron transfer is observed in the presence of testosterone, with the fast phase, representing 90% of the total absorbance change, having a rate of 14±2 s−1. Measurements of the first electron transfer were performed at various molar ratios of CPR/CYP3A4 in proteoliposomes; the rate was unaffected, consistent with a model in which first electron transfer takes place within a relatively stable CPR–CYP3A4 complex. Steady-state rates of NADPH oxidation and of 6β-hydroxytestosterone formation were also measured as a function of the molar ratio of CPR/CYP3A4 in the proteoliposomes. These rates increased with increasing CPR/CYP3A4 ratio, showing a hyperbolic dependency indicating a Kd (app) of ~0.4 μM. This suggests that the CPR–CYP3A4 complex can dissociate and reform between the first and second electron transfers.

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