Monoclonal antibody-directed immunopurification and identification of cytochromes P-450

Several rat liver cytochromes P-450 have been substantially purified in a one-step immunoadsorption procedure using Sepharose-bound monoclonal antibodies (MAbs) to the major forms of rat liver cytochrome P-450 induced by 3-methylcholanthrene and phenobarbital (MC-P-450 and PB-P-450, respectively). When mixed with solubilized rat liver microsomes the immunoadsorbent based on the MAb to MC-P-450 binds two polypeptides of MW 56,000 and 57,000 while the immunoadsorbent made with the MAb to PB-P-450 absorbs a species of MW 54,000. These polypeptides are readily desorbed by 0.1 M glycine (pH 3.0). Isolation of MAb-specific cytochrome P-450 isozymes by this method has applications in numerous phases of cytochrome P-450 research.