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5137126 
Journal Article 
Separation and purification of multiple forms of microsomal cytochrome P-450: Activities of different forms of cytochrome P-450 towards several compounds of environmental interest 
Guengerich, FP 
1977 
Yes 
Journal of Biological Chemistry
ISSN: 0021-9258
EISSN: 1083-351X 
252 
11 
3970-3979 
English 
HEEP COPYRIGHT: BIOL ABS. A new procedure was devised for the separation and purification of the cytochromes P-450 from the hepatic microsomes of male rats, based on the initial procedures of Imai and Sato. Isolated fractions range in nominal specific content (nanomoles of cytochrome P-450 per mg of protein) from 6.8-15.4 for phenobarbital-treated rats, from 3.7-14.9 for 3-methylcholanthrene-treated rats and from 5.6-11.7 for untreated rats. Several of the fractions approach apparent homogeneity as judged by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. A number of cytochromes P-450 from rabbit liver and lung were also highly purified by modifications of existing procedures. With both the rat and rabbit systems, a number of different cytochromes P-450 can be distinguished in various cases by their behaviors in the fractionation systems, spectral properties and apparent subunit MW. In certain cases, enzymes are indistinguishable by a single criterion, but differences can be demonstrated by other of the techniques. All the various cytochrome P-450 fractions (when coupled with highly purified preparations of NADPH-cytochrome P-450 reductase (NADPH:ferricytochrome oxidoreductase, EC 1.6.2.4), synthetic phospholipid and deoxycholate) are active in catalyzing the mixed-function oxidation of various compounds of environmental interest. Various specificity profiles were observed with the different reconstituted cytochrome P-450 systems from the rat and rabbit for the demethylations of d-benzphetamine, dimethylnitrosamine, N-methyl-4-aminoazobenzene and N,N-dimethyl-4-aminoazobenzene, the hydroxylation of benzo(a)pyrene, the oxidation of the pyrrolizidine alkaloid lasiocarpaine, the conversion of the insecticide parathion to paraoxon, diethylphosphorothionate and diethylphosphate, the transformation of aflatoxin B1 to species covalently bound to DNA, and the metabolism of the toxic furans 4-ipomeanol and 2-(N-ethylcarbamoylhydroxymethyl)-furan to products covalently bound to protein.