Characterization of Pulmonary CYP4B2, Specific Catalyst of Methyl Oxidation of 3-Methylindole

The selective toxicity of chemicals to lung tissues is predomi-nately mediated by the selective expression of certain pulmo-nary cytochrome P450 enzymes. This report describes the purification, cloning, and characterization of a unique enzyme, CYP4B2, from goat lung. The purified P450 enzyme was iso-lated by multistep ion exchange chromatography to electro-phoretic homogeneity with an apparent molecular mass of 55,000 Da. Western blotting studies demonstrated that CYP4B enzymes were selectively expressed in lung tissues of rabbits, rats, and mice. Two cDNAs, CYP4B2 and CYP4B2v, were cloned from goat lung tissue. CYP4B2 was predicted to be 511 amino acids and approximately 82 % similar to the four known CYP4B1 proteins. Concurrently, a variant of the known human CYP4B1 cDNA, that contained a S207 insertion, was clone