Detection and purification of cytochromes P-450 in animal tissues with monoclonal antibodies.

Monoclonal antibody (MAb)-based radioimmunoassay (RIA) and immunopurification procedures were used to probe the immunochemical relatedness of cytochromes P-450 in tissues from different species. RIAs based on MAb 1-7-1 and MAb 1-31-2, both to the major 3-methylcholanthrene (MC)-induced rat liver microsomal cytochrome P-450, detected antigenically related forms of cytochrome P-450 in liver microsomes from MC-induced rats, C57BL/6 and DBA/2 mice, hamsters, and guinea pigs, and in lung and kidney microsomes of MC-induced rats. Individual cytochromes P-450 were also isolated from these microsomes by MAb-directed immunopurification. When bound to Sepharose, MAb 1-7-1 adsorbed two species of Mr 56,000 and 57,000 from liver microsomes from rats and C57BL/6 mice, while MAb 1-31-2 adsorbed only the Mr 57,000 polypeptide. These results reveal that livers from both rats and C57BL/6 mice contain a cytochrome P-450 (Mr 56,000) with the epitope for 1-7-1 and a cytochrome P-450 (Mr 57,000) with epitopes for both 1-31-2 and 1-7-1. Additional immunochemical relatedness between the cytochromes P-450 in different tissues was demonstrated by MAb-directed immunopurification of cytochromes P-450 from DBA/2 mouse liver (Mr 56,000), guinea pig liver (Mr 53,000), hamster liver (Mr 57,000), and rat lung (Mr 57,000). These results demonstrate the efficacy of MAb-based RIA and immunopurification procedures for simple and rapid detection and purification of cytochromes P-450 from a variety of tissues.