Multiplicity of cytochrome P-450 hemoproteins in rat liver microsomes. Preparation and specificity of an antibody to the hemoprotein induced by phenobarbital.

摘要: Rat liver microsomes have previously been shown to contain hemoproteins having molecular weights of 53,000, 50,000, and 45,000. The 45,000-dalton hemoprotein, which is induced in rat by pretreatment animals with phenobarbital, resistant proteolysis trypsin. This characteristic was used purify it from the other microsomal hemoproteins. In procedure used, a sodium cholate-solubilized fraction phenobarbital-pretreated rats treated trypsin chromatographed on Sephadex G-100 separate hemoprotein preolytic degradation products. thus isolated homogenous basis dodecyl sulfate-polyacrylamide gel electrophoresis identified spectrally as cytochrome P-420 hemoprotein. free b5 NADPH-cytochrome c reductase activity. Antibody prepared against protease-treated will not cross-react 53,000- 50,000-dalton assessed three criteria. First, immunoprecipitation studies were conducted detergent-solubilized partially purified P-450 preparations control phenobarbital- 3-methylcholathrene-retreated rats. antibody immunoprecipitated only these preparations, each contains all Second, demonstrated specificity regard hydroxylation reactions would inhibit reconstituted system containing (448) fractions or 3-methylcholathrene-pretreated benzphetamine-N-demethylation catalyzed both but benzpyrene either. Third, agglutination complement fixation assays performed assess binding 3- methylcholanthrene-pretreated These that binds preferentially rats, has be induced. It hypothesized there are very significant structural catalytic differences among