Chromatographic and catalytic properties of multiple forms of rabbit pulmonary cytochromes P‐450

Abstract

Rabbit pulmonary cytochrome P-450 forms 2, 5, and 6 were resolved using anion-exchange high-performance liquid chromatography (HPLC) and their properties compared with rabbit liver cytochrome P-450 isozymes LM2 and LM6. Although rabbit pulmonary form 2 and liver LM2 had similar electrophoretic mobilities and similar substrate specificities in reconstitution experiments, they differed in their HPLC elution profiles. High-performance liquid chromatography of pulmonary microsomes from rabbits treated with 3-methylcholanthrene (3-MC) revealed the induction of form 6 isozyme, which had a retention time, electrophoretic mobility, and substrate specificity similar to those of rabbit liver LM6. In reconstitution experiments, forms 2 and 6 showed the highest substrate specificities toward benzphetamine and 7-ethoxyresorufin, respectively. Rabbit lung cytochrome P-450 form 5 was relatively inactive toward all substrates tested.