Faculty Scholarship (PHRM)
 

Title

A comparison of substrate dynamics in human CYP2E1 and CYP2A6

Document Type

Article

Publication/Creation/Presentation Date

2007

Journal

Biochemical and biophysical research communications

Volume

352

Issue

4

Disciplines

Pharmacy and Pharmaceutical Sciences

Abstract

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(0)- and d(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(H)/k(D))(obs) for d(3)-p-xylene oxidation ((k(H)/k(D))(obs)=6.04 and (k(H)/k(D))(obs)=5.53 for CYP2E1 and CYP2A6, respectively) was only slightly higher than (k(H)/k(D))(obs) for d(3)-dimethylnaphthalene ((k(H)/k(D))(obs)=5.50 and (k(H)/k(D))(obs)=4.96, respectively). One explanation is that in some instances (k(H)/k(D))(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.

Comments

Biochem Biophys Res Commun. Author manuscript; available in PMC 2009 August 17. Published in final edited form as: Biochem Biophys Res Commun. 2007 January 26; 352(4): 843–849. Published online 2006 November 27. doi: 10.1016/j.bbrc.2006.11.071.