Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

A requirement for dietary lipids for induction of cytochrome P-450 by phenobarbitone in rat liver microsomal fraction.

ABSTRACT: 1. Rats fed on purified synthetic diets have a markedly lower cytochrome P-450 concentration and hydroxylating enzyme activity in liver microsomal fraction than rats fed on stock pellets. 2. When both groups are treated with phenobarbitone the difference is even greater, the purified diet allowing only 50% of the cytochrome P-450 concentrations of controls. 3. Addition of herring oil, linoleic acid or 0.1% oxidized sitosterol to the diets allows induction of cytochrome P-450 to take place. 4. Addition of coconut oil to the diet does not permit induction of cytochrome P-450. 5. The interactions between dietary protein and the lipid substances are explored. 6. The mechanism of induction of microsomal hydroxylation enzymes by drugs is discussed in the light of these requirements.

SUBMITTER: Marshall WJ

PROVIDER: S-EPMC1176815 | biostudies-other | 1971 May

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Phospholipid requirement for 2-acetamidofluorene N-and ring-hydroxylation by hamster liver microsomal cytochrome P-450 enzyme system.

Project description:A phospholipid requirement of 2-acetamidofluorene N- and ring-hydroxylation was investigated with partially delipidated microsomal fraction from livers of 3-methylcholanthrene-pretreated hamsters. Butan-1-ol extraction of microsomal fraction removed 90% of the total lipid content without any appreciable effect on microsomal proteins. Such extracted microsomal fractions had much lower capacity to N- and ring-hydroxylate 2-acetamidofluorene: 25 and 44% of control respectively. Addition of butan-1-ol-extracted total lipid restored both oxidations to some extent, whereas addition of phosphatidylcholine fraction restored both oxidations almost completely. Addition of synthetic phospholipid, dilauroyl phosphatidylcholine, restored both oxidations to a large extent, whereas synthetic dipalmitoyl or distearoyl phosphatidylcholine was ineffective in restoring these oxidations.

| S-EPMC1183807 | biostudies-other

Induction by phenobarbital of the mRNA for a specific variant of rat liver microsomal cytochrome P-450.

Project description:The treatment of rats for 4 days with phenobarbital causes an apparent 3-fold increase in the amount of total liver cytochrome P-450. By sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, metyrapone binding and immunoprecipitation, this increase was found to be due to a much larger increase in a restricted number of specific cytochrome P-450 variants. A radioimmunoassay technique demonstrated that the major phenobarbital-inducible variant, of molecular weight 52 000, is induced 24-fold by phenobarbital. Immunoprecipitation analysis of products of translation in vitro with an antibody specific to the 52 000-mol.wt. cytochrome P-450 showed that phenobarbital induces the mRNA in polyribosomes for this variant 20-fold. Evidence is presented for the action of phenobarbital at the transcriptional and translational levels.

| S-EPMC1163106 | biostudies-other

Phospholipid requirement for dimethylnitrosamine demethylation by hamster hepatic microsomal cytochrome P-450 enzyme system.

Project description:Extraction with butan-1-ol of freeze-dried microsomal fractions from livers of 3-methyl-cholarthrene-pre-treated hamsters removed about 90% of the total lipid content, but the lipid remaining proved sufficient for the cytochrome P-450 enzyme system to retain about 15-40% of its original catalytic activity for dimethylnitrosamine demethylation. Addition of butan-1-ol-extracted total phospholipid or phosphatidylcholine could not restore any activity, whereas the addition of the synthetic phospholipid dilauroyl phosphatidylcholine was able to restore almost complete activity. Synthetic dipalmitoyl or distearoyl phosphatidylcholine was ineffective in restoring the activity in this reconstituted system.

| S-EPMC1164247 | biostudies-other

Purification and characterization of the NADPH-cytochrome P-450 (cytochrome c) reductase from higher-plant microsomal fraction.

Project description:NADPH-cytochrome P-450 (cytochrome c) reductase (EC 1.6.2.4) was solubilized by detergent from microsomal fraction of wounded Jerusalem-artichoke (Helianthus tuberosus L.) tubers and purified to electrophoretic homogeneity. The purification was achieved by two anion-exchange columns and by affinity chromatography on 2',5'-bisphosphoadenosine-Sepharose 4B. An Mr value of 82,000 was obtained by SDS/polyacrylamide-gel electrophoresis. The purified enzyme exhibited typical flavoprotein redox spectra and contained equimolar quantities of FAD and FMN. The purified enzyme followed Michaelis-Menten kinetics with Km values of 20 microM for NADPH and 6.3 microM for cytochrome c. In contrast, with NADH as substrate this enzyme exhibited biphasic kinetics with Km values ranging from 46 microM to 54 mM. Substrate saturation curves as a function of NADPH at fixed concentration of cytochrome c are compatible with a sequential type of substrate-addition mechanism. The enzyme was able to reconstitute cinnamate 4-hydroxylase activity when associated with partially purified tuber cytochrome P-450 and dilauroyl phosphatidylcholine in the presence of NADPH. Rabbit antibodies directed against plant NADPH-cytochrome c reductase affected only weakly NADH-sustained reduction of cytochrome c, but inhibited strongly NADPH-cytochrome c reductase and NADPH- or NADH-dependent cinnamate hydroxylase activities from Jerusalem-artichoke microsomal fraction.

| S-EPMC1146696 | biostudies-other

Dimethylnitrosamine demethylation by reconstituted liver microsomal cytochrome P-450 enzyme system.

Project description:Oxidative demethylation of dimethylnitosamine was studied with both reconstituted and unresolved liver microsomal cytochrome P-450 enzyme systems from rats and hamsters. Proteinase treatment of liver microsomal preparations yielded cytochrome P-450 particulate fractions. Both cytochrome P-450 and NADPH- cytochrome c reductase fractions were required for optimum demethylation activity. Particulate cytochrome P-450 fractions were more effecient than either Triton X-100- or cholatesolubilized preparations of these particles in demethylation activity with rat and hamster liver preparations appear to be due to differences in specificity in their cytochrome P-450 fractions.

| S-EPMC1172528 | biostudies-other

Histidine residues in rabbit liver microsomal cytochrome P-450 2B4 control electron transfer from NADPH-cytochrome P-450 reductase and cytochrome b5.

Project description:Treatment of cytochrome P-450 2B4 (P-450 2B4) with diethylpyrocarbonate to introduce 10-11 equivalents of acylating agent per polypeptide chain resulted in the selective derivatization of histidine residues characterized by differential susceptibility toward the modifier. Second-derivative spectral analysis as well as fluorescence measurements disproved gross alterations in P-450 2B4 structure as a consequence of labelling. The modified haemoprotein retained its ability to bind hexobarbital and catalyse cumene hydroperoxide-sustained N-demethylation of the barbiturate. However, there was a steady attenuation of NAD(P)H-driven electron flux with increasing extent of P-450 2B4 carbethoxylation in reconstituted systems fortified with either NADPH-cytochrome P-450 reductase or NADH-cytochrome b5 reductase/cytochrome b5 as the redox partners, with 50% inhibition occurring when 6-7 histidines were blocked. Hampered P-450 2B4 reductase activities recovered to differing degrees upon treatment of the acylated mono-oxygenase with neutral hydroxylamine. Spectral data indicated that docking of the redox components to derivatized P-450 2B4 was not perturbed, so that disruption of the electron flows most likely resulted from some injury of the electron-transfer mechanisms.

| S-EPMC1217696 | biostudies-other

The cell-free synthesis of cytochrome c by a microsomal fraction from rat liver.

Project description:Conditions were investigated for demonstrating the synthesis in vitro of the complete molecule of cytochrome c by isolated liver microsomal systems from partially hepatectomized rats. It was first found that in vivo the early labelled cytochrome c associated with the microsomal fraction required, by comparison with the mitochondrial pool, more drastic conditions of extraction and its binding was less affected by freezing and thawing of the subcellular particles. The procedure of extraction and purification of cytochrome c had to be modified accordingly, to assure the recovery of the recently synthesized molecule. Several subcellular fractions were isolated from regenerating liver with a homogenization medium containing either 5 or 10mm-Mg(2+) and most of them were active in the synthesis of the cytochrome c apoprotein. The microsomal fraction, in the presence of either cell sap or pH5.0 fraction, was also able to incorporate [(59)Fe]haemin, delta-amino[(3)H]laevulic acid and (55)Fe into the prosthetic group of cytochrome c. These experiments confirm firmly the conclusions of our previous results obtained in vivo showing that both the apoprotein and the haem moieties are made and linked together on cytoplasmic ribosomes and only then is the complete molecule transferred to the mitochondria.

| S-EPMC1177245 | biostudies-other

Cloning of cytochrome P-450 2C9 cDNA from human liver and its expression in CHL cells.

Project description:AIM:Using bacterial, yeast, or mammalian cell expressing a human drug metabolism enzyme would seem good way to study drug metabolism-related problems. Human cytochrome P-450 2C9(CYP2C9) is a polymorphic enzyme responsible for the metabolism of a large number of clinically important drugs. It ranks among the most important drug metabolizing enzymes in humans. In order to provide a sufficient amount of the enzyme for drug metabolic research, the CYP2C9 cDNA was cloned and expressed stably in CHL cells. METHODS:After extraction of total RNA from human liver tissue, the human CYP2C9 cDNA was amplified with reverse transcription-polymerase chain reaction (RT-PCR), and cloned into cloning vector pGEM-T. The cDNA fragment was identified by DNA sequencing and subcloned into a mammalian expression vector pREP9. A transgenic cell line was established by transfecting the recombinant vector of pREP9-CYP2C9 into CHL cells. The enzyme activity of CYP2C9 catalyzing oxidation of tolbutamide to hydroxy tolbutamide in S9 fraction of the cell was determined by high performance liquid chromatography(HPLC). RESULTS:The amino acid sequence predicted from the cDNA segment was identical to that of CYP2C9*1, the wild type CYP2C9. However, there were two base differences, i.e. 21T>C, 1146C>T, but the encoding amino acid sequence was the same, L7, P382. The S9 fraction of the established cell line metabolizes tolbutamide to hydroxy tolbutamide; tolbutamide hydroxylase activity was found to be 0.465 +/- 0.109 micromol.min(-1).g(-1) S9 protein or 8.62 +/- 2.02mol.min(-1).mol(-1) CYP, but was undetectable in parental CHL cell. CONCLUSION:The cDNA of human CYP2C9 was successfully cloned and a cell line of CHL- CYP2C9, efficiently expressing the protein of CYP2C9, was established.

| S-EPMC4658375 | biostudies-literature

Role of haem in the induction of cytochrome P-450 by phenobarbitone. Studies in chick embryos in ovo and in cultured chick embryo hepatocytes.

Project description:The role of haem synthesis during induction of hepatic cytochrome P-450 haemoproteins was studied in chick embryo in ovo and in chick embryos hepatocytes cultured under chemically defined conditions. 1. Phenobarbitone caused a prompt increase in the activity of 5-aminolaevulinate synthase, the rate-limiting enzyme of haem biosynthesis, and in the concentration of cytochrome P-450. This induction response occurred without measurable initial destruction of the haem moiety of cytochrome P-450. 2. When intracellular haem availability was enhanced by exogenous haem or 5-aminolaevulinate, phenobarbitone-medicated induction of cytochrome P-450 was not affected in spite of the well known repression of 5-aminolaevulinate synthase by haem. These data are consistent with the concept that haem does not regulate the synthesis of cytochrome P-450 haemoproteins. 3. Acetate inhibited haem biosynthesis at the level of 5-aminolaevulinate formation. When intracellular haem availability was diminished by treatment with acetate, phenobarbitone-medicated induction was decreased. 4. This inhibitory effect of acetate on cytochrome P-450 induction was reversed by exogenous haem or its precursor 5-aminolaevulinate. These data suggest that inhibition of haem biosynthesis does not decrease synthesis of apo-cytochrome P-450. Moreover, they indicate that exogenous haem can be incorporated into newly formed aop-cytochrome P-450.

| S-EPMC1163251 | biostudies-other

Analysis of polymorphisms of canine Cytochrome P 450-CYP2D15.

Project description:Cytochrome P450 (CYP) proteins constitute a large ancient family of oxidative enzymes essential for the efficient elimination of a wide variety of clinically used drugs. Polymorphic variants of human CYP2D6 are associated with the conversion rate and efficacy of several drugs such as antidepressants. Polymorphisms of the canine orthologue CYP2D15 are of interest because these antidepressants are also used in dogs with behavioral problems and the outcome of the treatment is variable. However, the annotated CYP2D15 gene is incomplete and inaccurately assembled in CanFam3.1, hampering DNA sequence analysis of the gene in individual dogs. We elucidated the complete exon-intron structure of CYP2D15 to enable comprehensive genotyping of the gene using genomic DNA. We surveyed variations of the gene in four diverse dog breeds and identified novel polymorphisms in exon 2 in border collies. Further investigation to establish the impact of these canine CYP2D15 polymorphisms on interindividual variability in expression and function of this metabolizing enzyme is now feasible. Further knowledge of CYP pharmacogenetics will help individualize therapy and thereby increase therapeutic efficacy, especially in the use of antidepressants in veterinary behavioral medicine.

| S-EPMC7689907 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data