Arachidonic and eicosapentaenoic acid metabolism by human CYP1A1: highly stereoselective formation of 17(R),18(S)-epoxyeicosatetraenoic acid

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Item Type:	Article
Title:	Arachidonic and eicosapentaenoic acid metabolism by human CYP1A1: highly stereoselective formation of 17(R),18(S)-epoxyeicosatetraenoic acid
Creators Name:	Schwarz, D., Kisselev, P., Ericksen, S.S., Szklarz, G.D., Chernogolov, A., Honeck, H., Schunck, W.H. and Roots, I.
Abstract:	Human cytochrome P450 1A1 (CYP1A1) and human NADPH-cytochrome P450 reductase were expressed and purified from Spodoptera frugiperda insect cells. A reconstituted enzymatically active system metabolized polyunsaturated fatty acids such as arachidonic (AA) and eicosapentaenoic acid (EPA). CYP1A1 was an AA hydroxylase which oxidizes this substrate at a rate of 650±10pmol/min/ nmol CYP1A1, with over 90% of metabolites accounted for by hydroxylation products and with 19-OH-AA as major product. Epoxyeicosatrienoic acid (EET), mainly 14,15-EET, accounted for about 7% of total metabolites. Unlike rat CYP1A1, the human enzyme exhibited no 20-OH-AA as product. In contrast, with EPA as substrate CYP1A1 was mainly an epoxygenase, oxidizing with over 68% of total metabolites EPA to 17(R),18(S)-epoxyeicosatetraenoic acid (17(R),18(S)-EETeTr). 19-OH-EPA accounted for about 31% of total metabolites. Significantly, the 17,18-olefinic bond of EPA was epoxidized to 17(R),18(S)-EETeTr with nearly absolute regio- and stereoselectivity. Molecular modeling analyses provided rationale for high efficiency of AA hydroxylation at C19 and its gradual decrease down to C14, as well as for the limited EPA 17(S),18(R) epoxidation due to unfavorable enzyme-substrate interactions. The absence of ω-hydroxylation for both substrates is not due to steric factors, but probably a consequence of different reactivities of ω and (ω-1) carbons for hydrogen abstraction. It is suggested that the capacity of human CYP1A1 to metabolize AA and EPA and its inducibility by polycyclic aromatic hydrocarbons may affect the production of physiologically active metabolites, in particular, in the cardiovascular system and other extrahepatic tissues including lung.
Keywords:	AA, Arachidonic Acid, CYP, CYP1A1, Cytochrome P450, EET, Eicosapentaenoic Acid, EPA, Epoxyeicosatrienoic Acid, HETE, Human Cytochrome P450 1A1, Human NADPH Cytochrome P450 Reductase, P450 Reductase, Sf9, Spodoptera Frugiperda Insect Cells, Animals, Rats
Source:	Biochemical Pharmacology
ISSN:	0006-2952
Publisher:	Elsevier
Volume:	67
Number:	8
Page Range:	1445-1457
Date:	1 January 2004
Official Publication:	https://doi.org/10.1016/j.bcp.2003.12.023
PubMed:	View item in PubMed

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