Components of the hepatic microsomal P-450 hemoprotein electron transfer system (TPNH-cytochrome c reductase and P-450 hemoprotein) and the microsomal cytochrome b5 electron transfer system (DPNH-cytochrome bs reductase and cytochrome bS) were solubilized using Triton N-101 and glycerol, and separated using DEAE-cellulose chromatography. Microsomal aniline hydroxylase activity was reconstituted...

Cytochrome P-450 content (nmol/g of liver) differed within regions of rat liver according to proximity to intrahepatically implanted Morris hepatoma 7795 or 5123D. Liver adjacent to tumor had higher microsomal cytochrome P-450 content, decreased DNA content (mg/g of liver), and unaltered cytochrome c reductase activity compared to histologically indistinguishable liver far-removed from the tumo...

Two genes that hybridize to the cDNA for alcoholinducible cytochrome P-450 form 3a (P-450ALC 1 have been isolated from a rabbit genomic library and characterized by restriction mapping, hybridization, and partial sequence analysis. The genes show extensive sequence similarity as judged by hybridization at high stringency to the coding region of P-450 3a cDNA. However , only gene 1 hybridizes un...

The ratios of the scoparone O-demethylation products scopoletin to isoscopoletin were determined for reconstituted complexes of NADPH-P-450 reductase and each of four P-450 isozymes in a 2:1 molar ratio with a 1:1 mixture of [7-O-methyl-14C]- and [6-O-methyl-14C]-scoparone as substrate. The two phenobarbital inducible forms P-450PB-B and P-450PB-D have a 1:0.8 +/- 0.05 scopoletin to isoscopolet...

A procedure is described for isolating submicrosomal particles from the livers of rabbits treated with phenobarbital, without the use of proteolytic or lipolytic enzymes. The preparation contains 2.5 mpmoles of P-450 per mg of protein, whereas the content of P-420 and cytochrome bs is less than 1% of this. The preparation shows no distinct TPNHor DPNH-cytochrome c reductase activity, but DPNH-f...

Fifteen xanthates with carbon chains of different lengths or substitutions, including the antiviral compound D609 (O-tricyclo[5.2. 1.0(2,6)]dec-9-yl-dithiocarbonate), were tested for their ability to inactivate cytochromes P-450 (P-450s) 2B1 and 2B6. All of the xanthates tested were found to inactivate P-450 2B1 in a time- and concentration-dependent manner. The rates of inactivation at 30 degr...

The 3-methylcholanthrene-transformed tumorigenic cell line, MCA-C3H/10T1/2 CL15 (MCA), expresses the novel benz(a)anthracene (BA)-inducible polycyclic aromatic hydrocarbon-metabolizing cytochrome P-450 (P-450-EF). The level of expression is comparable to that reported for the nontumorigenic C3H/10T1/2 CL8 (10T1/2) cells (Pottenger, L. H., Christou, M., and Jefcoate, C. R. Arch. Biochem. Biophys...

A form of cytochrome P-450 catalyzing lanosterol 14a-demethylation (tentatively called ‘P’45014DMn) was purified from microsomes of semi-anaerobically grown cells of Saccharomyces cerevisiae to gel electrophoreitc homogeneity. An apparent monomeric M. = 58,000 was estimated for the purified cytochrome by sodium dodecyl sulfate-polyacrylamide g l electrophoresis. Both optical and EPR spectra of ...

NADPH-fortified human liver microsomes were examined with regard to ability to detoxicate several chemicals that do not require enzymatic oxidation to elicit a genotoxic response in a Salmonella typhimurium TA1535/pSK1002 system where umu response is used as an indicator of DNA damage. Microsomes did not affect the response seen with daunomycin, mitomycin C, 2,4,7-trinitro-9-fluorene, 1-nitropy...