title: Leukotriene B4 omega-side chain hydroxylation by CYP4F5 and CYP4F6.
abstract: Leukotriene B(4) (LTB(4)) is a lipid mediator that plays an important role in inflammation. Metabolism of LTB(4) by cytochrome P450 (CYP) enzymes belonging to the CYP4F subfamily is considered to be of importance for the regulation of inflammation. This study investigates LTB(4) metabolism by recombinant rat CYP4F5 and CYP4F6 expressed in a yeast system and by microsomes isolated from rat organs expressing CYP4F mRNA. CYP4F6 was found to convert LTB(4) into 19-hydoxy- and 18-hydroxy-LTB(4) with an apparent K(m) of 26 microM, and CYP4F5 was found to convert LTB(4) primarily into 18-hydroxy-LTB(4) with an apparent K(m) of 9.7 microM. The rate of formation of 18-hydroxy-LTB(4) by CYP4F5 was surprisingly high. At a substrate concentration of 30 microM, the rate of formation was about 15 nmol/min/mg microsomal protein, approximately 30 times faster than the reaction catalyzed by CYP4F6. Analysis of LTB(4) metabolism by microsomes isolated from various tissues from the rat suggests that CYP4F5 and CYP4F6 are active in the lung and to some extent in the brain, kidney, and testis. CYP4F5 and CYP4F6, due to their capacities to metabolize LTB(4), may play important roles in modulating inflammatory response in these organs.
authors.affiliation: Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA. jbylund@mcw.edu
authors.forename: Johan
authors.initials: J
authors.lastname: Bylund
authors.forename: Adam G
authors.initials: AG
authors.lastname: Harder
authors.forename: Kristopher G
authors.initials: KG
authors.lastname: Maier
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Roman
authors.forename: David R
authors.initials: DR
authors.lastname: Harder
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D002853:Chromatography, Liquid; D003001:Cloning, Molecular; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D000072470:Cytochrome P450 Family 4; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D008401:Gas Chromatography-Mass Spectrometry; D007668:Kidney / Q000378:metabolism; D007700:Kinetics; D007975:Leukotriene B4 / Q000737:chemistry*; D008297:Male; D008861:Microsomes / Q000378:metabolism; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D013997:Time Factors
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D011994:Recombinant Proteins; D007975:Leukotriene B4; D003577:Cytochrome P-450 Enzyme System; C465482:Cyp4f5 protein, rat; C473665:Cyp4f6 protein, rat; D000072470:Cytochrome P450 Family 4