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The broad substrate specificity of the cytochrome P450 (P450) enzyme superfamily of heme-thiolate proteins lends itself to diverse environmental and pharmaceutical applications. Until recently, the primary drawback in using living bacteria to catalyze mammalian P450-mediated reactions has been the paucity of electron transport from NADPH to P450 via(More)
Formation of four oxidative metabolites from the anticonvulsant drug phenytoin (DPH) catalyzed by human liver microsomal cytochrome P450 (P450) enzymes was determined simultaneously. Under the conditions in which linearity for formation of 4'-hydroxylated DPH (4'-HPPH; main metabolite) was observed, human liver cytosol increased microsome-mediated DPH(More)
A variety of polycyclic aromatic hydrocarbons and their dihydrodiol derivatives, arylamines, heterocyclic amines, and nitroarenes, were incubated with cDNA-based recombinant (Escherichia coli or Trichoplusia ni) systems expressing different forms of human cytochrome P450 (P450 or CYP) and NADPH-P450 reductase using Salmonella typhimurium tester strain(More)
The cytochrome P450 (P450)-mediated biotransformation of tamoxifen is important in determining both the clearance of the drug and its conversion to the active metabolite, trans-4-hydroxytamoxifen. Biotransformation by P450 forms expressed extrahepatically, such as in the breast and endometrium, may be particularly important in determining tissue-specific(More)
A full-length human cytochrome P450 (P450) 3A4 cDNA clone and four derivatives in which the N-terminus was modified were inserted into a pCW vector and used to transform Escherichia coli DH5 alpha cells. Little expression was seen with the native sequence; the highest level of expression (range of 40-110 membrane-bound nmol P450 liter-1) was achieved with a(More)
NADH-dependent 7-ethoxycoumarin O-deethylation activities could be reconstituted in systems containing cytochrome b5 (b5), NADH-b5 reductase, and bacterial recombinant P450 2E1 in 100 mM potassium phosphate buffer (pH 7.4) containing a synthetic phospholipid mixture and cholate. Replacement of NADH-b5 reductase with NADPH-P450 reductase yielded a 4-fold(More)
Cytochrome P450 1B1 (CYP1B1) participates in the metabolic activation of a number of procarcinogens including benzo[a]pyrene and the hydroxylation of 17beta-estradiol at the C-4 position. In this study, we investigated the association between CYP1B1 genetic polymorphism and breast or lung cancer incidence. The Ala-Ser polymorphism at codon 119 in presumed(More)
Bacterial systems have long been of use in toxicology. In addition to providing general models of enzymes and paradigms for biochemistry and molecular biology, they have been adapted to practical genotoxicity assays. More recently, bacteria also have been used in the production of mammalian enzymes of relevance to toxicology. Escherichia coli has been used(More)
Recombinant human enzymes expressed in membranes obtained from Escherichia coli transformed with cytochrome P450 (P450) and NADPH-P450 reductase cDNAs were used to identify the human P450 enzymes that are most active in catalyzing the oxidative transformation of benzo[a]pyrene in vitro. Activation of benzo[a]pyrene to genotoxic products that cause induction(More)
Echinacea preparations are widely used herbal remedies for the prevention and treatment of colds. In this study we have investigated the metabolism by human liver microsomes of the alkylamide components from an Echinacea preparation as well as that of pure synthetic alkylamides. No significant degradation of alkylamides was evident in cytosolic fractions.(More)