CYTOCHROME-P-450 2E1 IN RAT-LIVER PEROXISOMES - DOWN-REGULATION BY ISCHEMIA REPERFUSION-INDUCED OXIDATIVE STRESS/

Cytochrome P-450 containing enzymes, known to be present in the endopl asmic reticulum and mitochondria, catalyze the oxidation of various co mpounds. In this study Eve have used highly purified peroxisomes (>95% ) to provide evidence by analytical cell fractionation, enzyme activit y, 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 peroxi somes (0.72 +/- 0.03 nmol/min/mg protein) and microsomes (0.58 +/- 0.0 3 nmol/min/mg protein) supports the conclusion that peroxisomes contai n significant amount of Cyp 2E1. This peroxisomal Cyp 2E1 was also ind uced in acetone-treated rat liver. The status of microsomal and peroxi somal 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 peroxis omes and its downregulation during ischemia/reperfusion describes a ne w role for this organelle in cytochrome P-450 related cellular metabol ism and in oxidative stress induced disease conditions. (C) 1997 Elsev ier Science Inc.