The formation of S-nitrosoglutathione (GSNO) from amyl nitrite and n-butyl nitrite was studied in rat liver microsomes, employing N-ethylmaleimide (MalNEt) as an activator and indomethacin as an inhibitor of microsomal glutathione S-transferase (GST). Rates were compared with GST activity measured with 1-chloro-2,4-dinitrobenzene (CDNB) as a substrate. MalNEt stimulated GST activity and the for...

Transgenic tobacco (Nicotiana tabacum cv Xanthi) plants expressing a genetically engineered fused enzyme between rat cytochrome P4501A1 (CYPlAl) and yeast NADPH-cytochrome P450 oxidoreductase were produced. The expression plasmid pCFC2 for the fused enzyme was constructed by insertion of the corresponding cDNA into the expression vector pNCOl under the control of the cauliflower mosaic virus 35...

Further studies of the induction of the liver microsomal drug-hydroxylating enzyme system by pretreatment of rats with various drugs are presented. The phenobarbital-induced increase in the microsomal content of CO-binding pigment and in the activities of TPNH-cytochrome c reductase and the oxidative demethylation of aminopyrine is proportional, within certain limits, to the amount of phenobarb...

Transgenic tobacco (Nicotiana tabacum cv Xanthi) plants expressing a genetically engineered fused enzyme between rat cytochrome P4501A1 (CYP1A1) and yeast NADPH-cytochrome P450 oxidoreductase were produced. The expression plasmid pGFC2 for the fused enzyme was constructed by insertion of the corresponding cDNA into the expression vector pNG01 under the control of the cauliflower mosaic virus 35...

We have studied 250 human liver biopsy samples to determine the ontogeny of the microsomal glucose-6-phosphatase (EC 3.1.3.9) system. Human hepatic glucose-6-phosphatase enzyme activity develops at 11 weeks' gestation and slowly increases to approximately 10% of adult activity at term. In the first week after birth, activity rises to adult values. Increases in enzyme activity coincide with incr...

The present work describes an accurate assay of the rate-limiting enzyme in bile acid synthesis, the cholesterol 7 alpha-hydroxylase, in human liver. The assay is based on isotope dilution-mass spectrometry, and endogenous microsomal cholesterol is used as the only substrate for the enzyme. Operative liver biopsies were obtained from patients undergoing elective cholecystectomy under highly sta...

Objective(s) Phosphatidate phosphohydrolase (PAP) catalyzes the dephosphorylation of phosphatidic acid to yield Pi and  diacylglycerol. Two different forms of PAP in rat hepatocyte have been reported. PAP1 is located in cytosolic and microsomal fractions and participates in the synthesis of triacylglycerols, phosphatidylcholine, and phosphatidylethanolamine, whereas the other form of phosphati...

Rifampicin is known to influence the metabolic disposition of other drugs because of its 'enzyme inducing' effects in the liver (1, 6). The microsomal enzymes catalyze glucuronide conjugations and most of the oxidation of the drugs. Reduction and hydrolysis of drugs are catalyzed by both microsomal and non-microsomal enzymes (3). Hydroxylation and glucuronide formation are involved in the metab...

The involvement of FMO in the N-oxygenation of CLZ was investigated by use of purified FMOs and human liver microsomes that contained the mean amount of immunoreactive FMO3 relative to other human liver microsomal preparations in a liver bank. In the microsomal preparation the involvement of FMO was indicated through enzyme inhibition by methimazole, heat inactivation, and protection against he...