Primary Structures and Regulation of Cytochrome P-450 Isozymes 2 (IIB) And 5 (IVB) and the Flavin-Containing Monooxygenase in Rabbit Liver and Lung

Abstract

Cytochrome P-450 (P-450) isozymes 2 and 5, which belong to P-450 gene subfamilies IIB and IVB according to the nomenclature devised by Nebert et al. (1), comprise over 90% of the P-450 in rabbit lung and are the major drug-metabolizing enzymes in that tissue. Results of immunochemical, catalytic, and biochemical studies (2-5) suggest that orthologs of isozymes 2 and 5 also account for the majority of the pulmonary P-450 in other species (rats, mice, guinea pigs, hamsters, and monkeys). A third drug-metabolizing enzyme present in rabbit lung at a relatively high concentration is the flavin-containing monooxygenase (FMO). This enzyme, which catalyzes the oxidation of sulfur, phosphorous, and nitrogen in a wide variety of compounds (6, 7), has also been detected in lungs from a number of species (8).