PURIFICATION AND CHARACTERIZATION OF HEPATIC P-450IIE1 FROM ACETONE-TREATED MICE

A new cytochrome P-450 isozyme (Mr = 52,000) was purified to apparent electrophoretic homogeneity from hepatic microsomes of mice treated with acetone and its biochemical, spectral, and immunological properties characterized. Several criteria indicated that the purified cytochrome was distinct from the known mouse P-450 isozymes. The absolute spectrum of its oxidized form indicated that it was in the high spin state. In a reconstituted system, it showed low catalytic activities towards 7-ethoxycoumarin, aminopyrine, and coumarin. whereas it catalyzed the oxidation of aniline, acetone, dimethylnitrosoamine with high turnover number. The mouse enzyme was immunoreactive with polyclonal antibodies against rat P-450IIE1 and exhibited an NH2-terminal aminoacid sequence with a high homology to that of rat-P-450IIE1. Based upon the above catalytic, spectral, immunological and structural properties, the purified mouse P-450 appears to be the ortholog of previously described P-450IIE1(s) of other species.