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...

Under margin assumptions, we prove several risk bounds, represented via the distribution depen-dent local entropies of the classes or the sizes of specific sample compression schemes. In somecases, our guarantees are optimal up to constant factors for families of classes. We discuss limi-tations of our approach and give several applications. In particular, we provide a new tight...

The properties of ceramide galactosyltransferase associated with myelin and microsomal fractions of rat brain were studied. The enzyme from both the fractions had similar properties during development and synthesized the same molecular species of the product cerebroside. The results suggested that during myelination the turnover rate of enzyme protein is altered instead of regulatory modulation...

Mammalian soluble and microsomal epoxide hydrolases have been proposed to belong to the family of alpha/beta-hydrolase-fold enzymes. These enzymes hydrolyse their substrates by a catalytic triad, with the first step of the enzymatic reaction being the formation of a covalent enzyme-substrate ester. In the present paper, we describe the direct visualization of the ester formation between rat mic...

A procedure for the purification of the enzyme bile acid:CoA ligase from guinea pig liver microsomes was developed. Activity toward chenodeoxycholate, cholate, deoxycholate, and lithocholate co-purified suggesting that a single enzyme form catalyzes the activation of all four bile acids. Activity toward lithocholate could not be accurately assayed during the earlier stages of purification due t...

OBJECTIVES Cytochrome P450 (CYP) 1A1 located in the membrane of endoplasmic reticulum is the most important enzyme in both activation and detoxification of carcinogenic benzo[a]pyrene (BaP), in combination with microsomal epoxide hydrolase (mEH). However, it is still not clearly explained how the electron transfer is mediated by NADPH:CYP oxidoreductase (POR), another component of the microsoma...

Glucose 6-phosphatase from rat liver and kidney microsomes previously has been shown to catalyze an inorganic pyrophosphate-glucose phosphotransferase reaction. Nordlie and Soodsma recently have suggested that formation and then degradation of glucose 6-phosphate by the combined action of phosphotransferase and phosphohydrolase activities of this enzyme may under certain conditions constitute p...

Characteristics of 3-hydroxy-3-methylglutaryl-CoA reductase from normal liver, Morris hepatomas 5123C, 5123t.c. and 9618A, and host liver were studied. Animals were fed on control and 5%-cholesterol diets. Microsomal membranes from all tissues were found to accumulate cholesterol after 3 days on the 5%-cholesterol diet. The enzyme of the tumours showed no feedback inhibition by dietary choleste...