Purification and characterization of a mouse liver cytochrome P-450 induced by cannabidiol.
A cytochrome P-450 isozyme (Mr = 51,600) was purified to apparent homogeneity from hepatic microsomes of mice pretreated with cannabidiol (CBD), a major constituent of marijuana. The isozyme exhibited high pentoxyresorufin O-dealkylase, hexobarbital hydroxylase, and 16 alpha- and 16 beta-testosterone hydroxylase activities and formed a Fe+2-metyrapone complex, properties characteristic of the major hepatic cytochrome P-450s previously purified from phenobarbital (PB)-pretreated animals. In addition, the CBD-induced cytochrome P-450 was immunoreactive with an antibody raised against the major rat hepatic PB-inducible cytochrome P-450 and exhibited an NH2-terminal amino acid sequence greater than 90% homologous with that of the PB-inducible rat liver isozyme. Because of the many similarities between the CBD-induced isozyme and certain other isozymes previously purified from PB-pretreated animals, a cytochrome P-450 isozyme was purified from PB-pretreated mice by a chromatographic procedure similar to that employed for purification of the CBD-induced isozyme. The PB-inducible isozyme was indistinguishable from the CBD-inducible cytochrome P-450 on the bases of apparent molecular weight, absorption spectra, NH2-terminal amino acid sequence, peptide mapping, immunoreactivity, and catalytic activity. Although the CBD- and PB-inducible P-450 isozymes appear to be qualitatively very similar, PB appears to be a quantitatively better inducer of the isozyme. Thus, CBD exposure results in the induction of an isozyme that is refractory to CBD-mediated inactivation, thereby apparently altering the cytochrome P-450 isozymal composition of mouse hepatic microsomes.
Department of Pharmacology, University of California, San Francisco 94143.
L M
LM
Bornheim
M A
MA
Correia
D000595:Amino Acid Sequence; D000818:Animals; D002185:Cannabidiol / Q000494:pharmacology*; D002186:Cannabinoids / Q000494:pharmacology*; D002384:Catalysis; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000302:isolation & purification*; D004790:Enzyme Induction / Q000187:drug effects; D015151:Immunoblotting; D051379:Mice; D008815:Mice, Inbred Strains; D008862:Microsomes, Liver / Q000201:enzymology; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D013057:Spectrum Analysis
D002186:Cannabinoids; D002185:Cannabidiol; D003577:Cytochrome P-450 Enzyme System