Preparation of catalytically active cytochromes P-450 by antigen exchange on monoclonal antibody based...

Catalytically active cytochromes P-450 have been prepared by monoclonal antibody (MAb) directed immunopurification using an antigen-exchange technique. Immunoaffinity-purified cytochromes P-450 that require denaturants for efficient desorption from the immunoaffinity matrix, although significantly lacking in catalytic activity, were found to retain epitopic structural integrity as probed by radioimmunoassay using MAbs to 3-methylcholanthrene and phenobarbital-induced rat liver cytochromes P-450. These denatured cytochromes P-450 were capable of displacing from the immunoaffinity matrices epitopically related cytochromes P-450 that retained aryl hydrocarbon hydroxylase and 7-ethoxycoumarin O-deethylase activities. Such epitope-specific exchange of denatured for native antigen on a solid-phase matrix containing a MAb may be generally applicable to preparation of proteins with the retention of activity.