A comparison of substrate dynamics in human CYP2E1 and CYP2A6

Journal Article · Fri Jan 26 04:00:00 EST 2007 · Biochemical and Biophysical Research Communications

DOI:https://doi.org/10.1016/j.bbrc.2006.11.071· OSTI ID:20857971

Harrelson, John P ^[1]; Henne, Kirk R ^[2]; Alonso, Darwin O.V. ^[1]; Nelson, Sidney D ^[1]

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1. Department of Medicinal Chemistry, University of Washington, Box 357610, Seattle, WA 98195 (United States)
2. Amgen, South San Francisco, CA 94080 (United States)

Considering the dynamic nature of CYPs, methods that reveal information about substrate and enzyme dynamics are necessary to generate predictive models. To compare substrate dynamics in CYP2E1 and CYP2A6, intramolecular isotope effect experiments were conducted, using deuterium labeled substrates: o-xylene, m-xylene, p-xylene, 2,6-dimethylnaphthalene, and 4,4'-dimethylbiphenyl. Competitive intermolecular experiments were also conducted using d{sub 0}- and d{sub 6}-labeled p-xylene. Both CYP2E1 and CYP2A6 displayed full isotope effect expression for o-xylene oxidation and almost complete suppression for dimethylbiphenyl. Interestingly (k {sub H}/k {sub D}){sub obs} for d{sub 3}-p-xylene oxidation ((k {sub H}/k {sub D}){sub obs} = 6.04 and (k {sub H}/k {sub D}){sub obs} = 5.53 for CYP2E1 and CYP2A6, respectively) was only slightly higher than (k {sub H}/k {sub D}){sub obs} for d{sub 3}-dimethylnaphthalene ((k {sub H}/k {sub D}){sub obs} = 5.50 and (k {sub H}/k {sub D}){sub obs} = 4.96, respectively). One explanation is that in some instances (k {sub H}/k {sub D}){sub obs} values are generated by the presence of two substrates-bound simultaneously to the CYP. Speculatively, if this explanation is valid, then intramolecular isotope effect experiments should be useful in the mechanistic investigation of P450 cooperativity.

• OSTI ID: 20857971
• Journal Information: Biochemical and Biophysical Research Communications, Journal Name: Biochemical and Biophysical Research Communications Journal Issue: 4 Vol. 352; ISSN BBRCA9; ISSN 0006-291X
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
DEUTERIUM
ENZYMES
INHIBITION
ISOTOPE EFFECTS
OXIDATION
SUBSTRATES
XYLENES