2,5-Diphenyloxazole as a probe for microsomal mono-oxygenation in human and rat liver. 1985

E Mutch, and K W Woodhouse, and F M Williams, and D Lambert, and O F James, and M D Rawlins

2,5-Diphenyloxazole (PPO) is metabolized to one major fluorescent product by human liver and rat liver microsomes. PPO metabolism by human-liver microsomes involves more than one cytochrome P-450 isozyme, termed low-affinity and high-affinity components. At a substrate concentration of 0.1 microM, 95% of activity is due to the high-affinity component whereas at 100 microM 69% of activity is due to the low-affinity component. Inhibition studies with metyrapone and alpha-naphthoflavone at 0.1 microM and 100 microM suggest that the high-affinity component may reflect a 3-methylcholanthrene-inducible form of cytochrome. Therefore studies at low substrate concentrations may be a useful tool for cytochrome P-450 studies in man. Rat liver microsomes show linear kinetics indicating the involvement of one major form of cytochrome P-450.

UI MeSH Term Description Entries
D007527 Isoenzymes Structurally related forms of an enzyme. Each isoenzyme has the same mechanism and classification, but differs in its chemical, physical, or immunological characteristics. Alloenzyme,Allozyme,Isoenzyme,Isozyme,Isozymes,Alloenzymes,Allozymes
D007700 Kinetics The rate dynamics in chemical or physical systems.
D008797 Metyrapone An inhibitor of the enzyme STEROID 11-BETA-MONOOXYGENASE. It is used as a test of the feedback hypothalamic-pituitary mechanism in the diagnosis of CUSHING SYNDROME. Methbipyranone,Methopyrapone,Metopiron,Metopirone,Métopirone,SU 4885
D008862 Microsomes, Liver Closed vesicles of fragmented endoplasmic reticulum created when liver cells or tissue are disrupted by homogenization. They may be smooth or rough. Liver Microsomes,Liver Microsome,Microsome, Liver
D010080 Oxazoles Five-membered heterocyclic ring structures containing an oxygen in the 1-position and a nitrogen in the 3-position, in distinction from ISOXAZOLES where they are at the 1,2 positions. Oxazole,1,3-Oxazolium-5-Oxides,Munchnones,1,3 Oxazolium 5 Oxides
D010105 Oxygenases Oxidases that specifically introduce DIOXYGEN-derived oxygen atoms into a variety of organic molecules. Oxygenase
D003577 Cytochrome P-450 Enzyme System A superfamily of hundreds of closely related HEMEPROTEINS found throughout the phylogenetic spectrum, from animals, plants, fungi, to bacteria. They include numerous complex monooxygenases (MIXED FUNCTION OXYGENASES). In animals, these P-450 enzymes serve two major functions: (1) biosynthesis of steroids, fatty acids, and bile acids; (2) metabolism of endogenous and a wide variety of exogenous substrates, such as toxins and drugs (BIOTRANSFORMATION). They are classified, according to their sequence similarities rather than functions, into CYP gene families (>40% homology) and subfamilies (>59% homology). For example, enzymes from the CYP1, CYP2, and CYP3 gene families are responsible for most drug metabolism. Cytochrome P-450,Cytochrome P-450 Enzyme,Cytochrome P-450-Dependent Monooxygenase,P-450 Enzyme,P450 Enzyme,CYP450 Family,CYP450 Superfamily,Cytochrome P-450 Enzymes,Cytochrome P-450 Families,Cytochrome P-450 Monooxygenase,Cytochrome P-450 Oxygenase,Cytochrome P-450 Superfamily,Cytochrome P450,Cytochrome P450 Superfamily,Cytochrome p450 Families,P-450 Enzymes,P450 Enzymes,Cytochrome P 450,Cytochrome P 450 Dependent Monooxygenase,Cytochrome P 450 Enzyme,Cytochrome P 450 Enzyme System,Cytochrome P 450 Enzymes,Cytochrome P 450 Families,Cytochrome P 450 Monooxygenase,Cytochrome P 450 Oxygenase,Cytochrome P 450 Superfamily,Enzyme, Cytochrome P-450,Enzyme, P-450,Enzyme, P450,Enzymes, Cytochrome P-450,Enzymes, P-450,Enzymes, P450,Monooxygenase, Cytochrome P-450,Monooxygenase, Cytochrome P-450-Dependent,P 450 Enzyme,P 450 Enzymes,P-450 Enzyme, Cytochrome,P-450 Enzymes, Cytochrome,Superfamily, CYP450,Superfamily, Cytochrome P-450,Superfamily, Cytochrome P450
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D001571 Benzoflavones Organic compounds containing a BENZENE ring attached to a flavone group. Some of these are potent arylhydrocarbon hydroxylase inhibitors. They may also inhibit the binding of NUCLEIC ACIDS to BENZOPYRENES and related compounds. The designation includes all isomers; the 7,8-isomer is most frequently encountered. Benzoflavone Compounds,Compounds, Benzoflavone

Related Publications

E Mutch, and K W Woodhouse, and F M Williams, and D Lambert, and O F James, and M D Rawlins
September 1987, Pharmacology & toxicology,
E Mutch, and K W Woodhouse, and F M Williams, and D Lambert, and O F James, and M D Rawlins
March 1976, Research communications in chemical pathology and pharmacology,
E Mutch, and K W Woodhouse, and F M Williams, and D Lambert, and O F James, and M D Rawlins
December 1992, Anesthesiology,
E Mutch, and K W Woodhouse, and F M Williams, and D Lambert, and O F James, and M D Rawlins
November 1979, Biochemical pharmacology,
E Mutch, and K W Woodhouse, and F M Williams, and D Lambert, and O F James, and M D Rawlins
October 1972, Biochimica et biophysica acta,
E Mutch, and K W Woodhouse, and F M Williams, and D Lambert, and O F James, and M D Rawlins
July 1985, Xenobiotica; the fate of foreign compounds in biological systems,
E Mutch, and K W Woodhouse, and F M Williams, and D Lambert, and O F James, and M D Rawlins
October 1984, The Biochemical journal,
E Mutch, and K W Woodhouse, and F M Williams, and D Lambert, and O F James, and M D Rawlins
October 2001, Chemical communications (Cambridge, England),
E Mutch, and K W Woodhouse, and F M Williams, and D Lambert, and O F James, and M D Rawlins
December 1984, Mutation research,
E Mutch, and K W Woodhouse, and F M Williams, and D Lambert, and O F James, and M D Rawlins
January 1997, Eksperimental'naia i klinicheskaia farmakologiia,
Copied contents to your clipboard!