NADPH-cytochrome P-450 oxidoreductase (CPR) is essential for the catalytic activity of cytochrome P-450 (P-450). On a molar basis, the amount of P-450 exceeds that of CPR in human liver. In this study, we investigated whether drug-drug interactions can occur as a result of competition between P-450 isozymes for this ancillary protein. For this purpose, combinations of P-450 isozymes were coexpr...

We expressed mouse cytochrome P1-450 and P3-450 using recombinant vaccinia virus gene expression system in HeLa cells that were devoid of significant basal levels of P-450. HeLa cells were infected with the recombinant vaccinia virus containing either mouse cytochrome P1-450 or P3-450 cDNA, and the cell lysates were analyzed for the kinetics of P-450 enzyme activity and protein expression at th...

A defining feature of glial cells has been their inability to generate action potentials. We show here that there are two distinct types of morphologically identical oligodendrocyte precursor glial cells (OPCs) in situ in rat CNS white matter. One type expresses voltage-gated sodium and potassium channels, generates action potentials when depolarized and senses its environment by receiving exci...

Phospholipid has been reported to be necessary for optimal catalytic activity of a number of mammalian cytochrome P-450 (P-450) systems. We also confirm that a number of individual phospholipids and mixtures, used as soluble monomers or phospholipid vesicles, show activation of 7-ethoxycoumarin O-deethylase activity by an enzyme system composed of rat liver microsomal P-450PB-B and NADPH-P-450 ...

The binding of thiol, thiolate, thioether, and disulfide sulfur donor ligands to ferric cytochrome P-450-CAM and myoglobin has been investigated by W-visible absorption, magnetic circular dichroism (MCD), and EPR spectroscopy. For ferric P-450, the binding of all sulfur donors is competitive with substrate binding. Addition of thiols to P-450 leads to interconvertible thiol or thiolate-bound sp...

Cytochrome P-450 was purified to a specific content of 16 nmol/mg of protein from bovine adrenal cortex microsomes by hydrophobic chromatography using an w-amino-n-octyl Sepharose column in the presence of Emulgen 913, a nonionic detergent. The purified preparation exhibited a single polypeptide band (Mr = 47,000 f 1,000) when submitted to sodium dodecyl sulfate-polyacrylamide gel electrophor...

Evidence is presented that the regulation of the cytochrome P-450(C17 alpha) of the steroid-17 alpha-monooxygenase and of the cytochrome P-450(cscc) of the cholesterol-monooxygenase by human choriogonadotropin (hCG) in vivo is mediated by differential mechanisms in the adult rat testis. An initial down-regulation of the cytochrome P-450(C17 alpha) but not of the P-450(cscc) can be demonstrated....