10.1021/bi061803n.s001
Rusty W. Kelley
Rusty W.
Kelley
Dongmei Cheng
Dongmei
Cheng
Wayne L. Backes
Wayne L.
Backes
Heteromeric Complex Formation between CYP2E1 and CYP1A2: Evidence for the
Involvement of Electrostatic Interactions<sup>†</sup>
American Chemical Society
2006
Heteromeric Complex Formation
CYP 2B
CYP 1A interaction
CYP 2E
CYP 1A
CYP 1A Evidence
P 450 enzymes
reconstituted system
P 450 enzyme
CYP 2E Synergism
EROD
heteromeric CYP 2E complexes
reconstituted systems
NADPH
CYP 2B CYP 1A
CYP 1A complexes
subsaturating reductase concentrations
CYP 1A moiety
reductase concentration
PROD
2006-12-26 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Heteromeric_Complex_Formation_between_CYP2E1_and_CYP1A2_Evidence_for_the_Involvement_of_Electrostatic_Interactions_sup_sup_/3038836
Mixed reconstituted systems containing CYP2B4, CYP1A2, and NADPH−cytochrome P450
reductase were previously shown to exhibit a dramatic inhibition of 7-pentoxyresorufin O-dealkylation
(PROD) when compared to simple reconstituted systems containing reductase and a single P450 enzyme,
results consistent with the formation of CYP1A2−CYP2B4 complexes where the reductase binds with
high affinity to the CYP1A2 moiety of the complex. In this report, we provide evidence for an interaction
between CYP1A2 and CYP2E1. Synergism of 7-ethoxyresorufin O-deethylation (EROD) and PROD was
observed when these P450s were combined in mixed reconstituted systems at subsaturating reductase
concentrations. Higher ionic strength attenuated the synergistic stimulation of both PROD and EROD in
mixed reconstituted systems, consistent with disruption of heteromeric CYP2E1−CYP1A2 complexes.
The effect of ionic strength was further examined as a function of reductase concentration. At lower ionic
strength, there was a significant synergistic stimulation of EROD. This synergistic stimulation diminished
with increasing reductase concentration, resulting in an additive response as reductase became saturating.
Interestingly, at high ionic strength, the synergism of EROD in the mixed reconstituted system was not
observed. In contrast, mixed reconstituted systems containing CYP2E1 and CYP2B4 did not provide
evidence for the formation of these heteromeric P450−P450 complexes. The synergistic stimulation
observed with the reductase−CYP1A2−CYP2E1 mixed reconstituted system is consistent with the
formation of a CYP1A2−CYP2E1 complex. Taken together with the lack of a kinetically detectable
interaction between CYP2B4 and CYP2E1, and the previously reported CYP1A2−CYP2B4 interaction,
these results suggest that CYP1A2 may facilitate the formation of complexes with other P450 enzymes.