Three forms of cytochrome P-450 were purified to homogeneity from liver microsomes of Wistar-strain rats treated with phenobarbital. They had minimum mol.wts. of 52 000, 53 000 and 54 000 as determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and are designated as P-450(L), P-450(M) and P-450(H) respectively. They were shown to be immunoidentical by Ouchterlony double-diffu...

Cyclophosphamide was administered to adult male rats (130 mg/kg, single i.p. injection) and its effects on the P-450 enzymes that contribute to the activation of this drug in rat liver were then assessed. P-450-mediated cyclophosphamide 4-hydroxylase activity in isolated rat liver microsomes decreased by approximately 70% over a 9-day period following drug treatment. This decrease was due to th...

The cytochrome P-450 dependent monooxygenase system of rat liver microsomes is investigated by light dosimetry (action spectroscopy). The scoparone-O-demethylation activity is enhanced by light and depends on the wavelength of the irradiating light. The relative increase of the activity (about 15%) by the irradiating light (approximately 0.5 mW/cm2) is maximal at a wavelength of 400 nm. The lig...

The hydroxyl radical-mediated oxidation of 5,S-dimethyl1-pyrroline N-oxide, benzene, ketomethiolbutyric acid, deoxyribose, and ethanol, as well as superoxide anion and hydrogen peroxide formation was quantitated in reconstituted membrane vesicle systems containing purified rabbit liver microsomal NADPHcytochrome P-450 reductase and cytochromes P-450 LM2, P-450 LMeb, or P-450 LM4, and in vesicle...

Somatic cell hybrids were made between mouse myeloma cells and spleen cells derived from BALB/c mice immunized with liver microsomal cytochrome P-450 purified from rats treated with 3-methylcholanthrene (MC-P-450). Thirty-seven independent hybrid clones among 66 tested produced mono clonal antibodies to the MC-P-450 as measured by radioimmunoassay. More than 10 of the monoclonal antibodies form...

The expression of P-450 4A isoforms responsible for the formation of 20-hydroxyeicosatetraenoic acid (20-HETE) was examined using the reverse transcription and polymerase chain reaction in various nephron segments and preglomerular arterioles microdissected from the kidneys of Sprague-Dawley rats. Expression of cytochrome P-450 4A1, 4A2, 4A3, and 4A8 mRNA could be detected in RNA extracted from...

Two independent radioimmunoassay techniques for the major phenobarbital-inducible cytochrome P-450 (PB P-450) of rat liver microsomal membranes are described. The first technique employs as the source of radiolabelled antigen the products of translation in vitro labelled with [35S]methionine. The second technique employs purified antigen labelled with 125I and is quicker, less expensive and mor...

The binding characteristics of substrate and effector ligands to testicular microsomal cytochrome P-450 (17 alpha-hydroxylase/C17-20 lyase) have been investigated by difference spectroscopy. Steroid products and their analogs induce oxygen-mediated damage of microsomal P-450 activities of cultured Leydig cells, whereas testosterone acetate protects P-450 from this damage [1]. Progesterone and 1...

We have isolated cDNA clones of the mRNA for cytochrome P-450(SCC), which catalyzes the side-chain cleavage reaction of cholesterol in bovine adrenal cortex mitochondria, by using synthetic oligonucleotides as probes. Sequence analysis of the cloned cDNAs enabled us to deduce the primary structure of the precursor form of P-450(SCC), which consisted of 520 amino acids and contained an extrapept...