title: Cytochrome P-450 2E1 in rat liver peroxisomes: downregulation by ischemia/reperfusion-induced oxidative stress.
abstract: Cytochrome P-450 containing enzymes, known to be present in the endoplasmic reticulum and mitochondria, catalyze the oxidation of various compounds. In this study we have used highly purified peroxisomes (> 95%) to provide evidence by analytical cell fractionation, enzyme activity, Western blot, and immunocytochemical analysis that cytochrome P-450 2E1 (Cyp 2E1) is present in peroxisomes. Similar specific activities of aniline hydroxylase, a Cyp 2E1-dependent enzyme, in purified peroxisomes (0.72 +/- 0.03 nmol/min/mg protein) and microsomes (0.58 +/- 0.03 nmol/min/mg protein) supports the conclusion that peroxisomes contain significant amount of Cyp 2E1. This peroxisomal Cyp 2E1 was also induced in acetone-treated rat liver. The status of microsomal and peroxisomal Cyp 2E1 was also examined following ischemia/reperfusion-induced oxidative stress. Ischemia alone had no effect; however, reperfusion following ischemia resulted in decrease in Cyp 2E1 both in microsomes and peroxisomes. This demonstration of cytochrome P-450 2E1 in peroxisomes and its downregulation during ischemia/reperfusion describes a new role for this organelle in cytochrome P-450 related cellular metabolism and in oxidative stress induced disease conditions.
authors.affiliation: Department of Pathology and Laboratory Medicine, Ralph H. Johnson V.A. Medical Center, Charleston, SC USA.
authors.forename: K
authors.initials: K
authors.lastname: Pahan
authors.forename: B T
authors.initials: BT
authors.lastname: Smith
authors.forename: A K
authors.initials: AK
authors.lastname: Singh
authors.forename: I
authors.initials: I
authors.lastname: Singh
mesh_terms: D000814:Aniline Compounds / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D019392:Cytochrome P-450 CYP2E1 / Q000378:metabolism*; D015536:Down-Regulation; D006900:Hydroxylation; D008099:Liver / Q000098:blood supply / Q000201:enzymology*; D008297:Male; D008830:Microbodies / Q000378:metabolism*; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism; D015388:Organelles; D018384:Oxidative Stress / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D000814:Aniline Compounds; D019392:Cytochrome P-450 CYP2E1; D009251:NADPH-Ferrihemoprotein Reductase; C023650:aniline