Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.9 (glucose-6-phosphatase)
3,081 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intraperitoneal administration of diazepame and phenazepame into rats /at a dose 50 mg/kg/ within 4 days did not induce liver microsomal enzymes. After administration of chlordiazepoxide at the same dose content of cytochrome P-450 was increased and the rate of dimethylaniline demethylation was elevated. Content of protein as well as NADPH-cytochrome-c-reductase and glucose-6-phosphatase activities were increased after intraperitoneal administration of all the preparations at a dose 100 mg/kg within 4 days. Experiments on the potentiation of hexenal effect demonstrated the decrease in the time of sleep in animals, treated with chlordiazepoxide at a dose 100 mg/kg of body weight.
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PMID:[Effect of 1,4-benzodiazepine tranquilizers on the activity of the hepatocyte hydroxylating complex and glucose-6-phosphatase in white rats]. 4 17

Differential centrifugation was applied to adult and foetal liver of monkey. Obtained fractions were: F1 (800 X g); F2 (12 500 X g); F3 (200 000 X g); and cell sap. Analysis of chemical compounds of these fractions shows that: (1) adult and foetal nucleic acids levels are similar; (2) there are more proteins in adult than in foetal hepatocytes; (3) most of the glycogen is located in F3; the foetal level is twenty times higher than the adult level. Plasma membrane enzymes (5'-nucleotidase, adenylate cyclase) show a nucleomicrosomic distribution. The distribution of alkaline phosphatase is not significant. Mitochondrial enzymes (monoamine oxydase, succinate cytochrome c reductase, cytochrome oxydase) are enriched in F2 without any sedimentation in F3. There is more malate dehydrogenase liberated in cell sap during foetal liver fractionation. This indicates the foetal mitochondria are more sensitive to the homogenisation method. Lysosomal enzymes (acid phosphatase, N-acetylglucosaminidase) are enriched in F2. The same observation for N-acetylglucosaminidase as for malate dehydrogenase leads to the same conclusion for foetal lysosomes. Endoplasmic reticulum and Golgi enzymes (glucose-6-phosphatase and related phosphotransferase activity, NADPH-cytochrome c reductase and sialytransferase) are much enriched in F3. Thus this fraction F3 is pure enough to allow the observation of the modification produced on endoplasmic reticulum and Golgi apparatus during foetal and neonatal development.
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PMID:[Comparative study of microsomal enzymic activities in adult and foetal monkey hepatocytes (author's transl)]. 11 30

Nuclei, nuclear membranes and rough endoplasmic reticulum (rER) were isolated from onion root tips and stems. Structural preservation and purity of the fractions was determined by electron microscopic and biochemical methods. Gross compositional data (protein, phospholipid, nonpolar lipids, sterols, RNA, DNA), phospholipid and fatty acid patterns, enzyme activities (ATPases, ADPase, IDPase, glucose-6-phosphatase, 5'-nucleotidase, acid phosphatase, and NADH- and NADPH-cytochrome C reductases), and cytochrome contents were determined. A stable, high salt-resistant attachment of some DNA with the nuclear membrane was observed as well as the association of some RNA with high salt-treated nuclear and rER membranes. The phospholipid pattern was identical for both nuclear and rER membranes and showed a predominance of lecithin (about 60%) and phosphatidyl ethanolamine (20-24%). Special care was necessary to minimize lipid degradation by phospholipases during isolations. Nonpolar lipids, mostly sterols and triglycerides, accounted for 35-45% of the membrane lipids. Sterol contents were relatively high in both membrane fractions (molar ratios of sterols to phospholipids ranged from 0.12 to 0.43). Sitosterol accounted for about 80% of the total sterols. Palmitic, oleic, and linoleic acids were the most prevalent acids in membrane-bound lipids as well as in storage lipids and occurred in similar proportions in phospholipids, triglycerides and free fatty acids of the membrane. About 80% of the fatty acids in membrane phospholipids and triglycerides were unsaturated. A cytochrome of the b5 type was characterized in these membranes, but P-450-like cytochromes could not be detected. Both NADH and NADPH-cytochrome c reductases were found in nuclear and rER membranes and appeared to be enriched in rER membranes. Among the phosphatases, Mg2+-ATPase and, to lesser extents, ADPase, IDPase and acid phosphatase activities occurred in the fractions, but significant amounts of monovalent ion-stimulated ATPase, 5'-nucleotidase and glucose-6-phosphatase activities did not. The results obtained emphasize that the close biochemical similarities noted between rER and nuclear membranes of animal cells extend to these fractions from plant cells.
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PMID:Characterization of nuclear membranes and endoplasmic reticulum isolated from plant tissue. 17 22

A primary objective of the present study has been to determine the changes which occur in Rana catesbeiana liver organelle membranes during thyroxine-induced metamorphosis. To this end, enzyme and cytochrome profiles were determined for mitochondria, microsomes, and nuclear membrane fractions isolated from livers of R. catesbeiana tadpoles which had been fasted for 6 days at 15 +/- 0.5 degrees and then immersed in thyroxine, 2.6 X 10(-8) M, for periods of up to 12 days at 23.5 +/- 0.4 degrees. The ratio of total succinate-cytochrome c reductase activity in the initial homogenate fraction to the total activity of this mitochondrial "marker" enzyme recovered in the final mitochondrial fraction remained constant, approximately 0.5, throughout the course of thyroxine treatment; however, after a 3- to 4-day latency the mitochondrial protein mass recovered per unit mass of initial homogenate protein was found to increase significantly (approximately 2-fold by Day 10 of thyroxine treatment). A similar increase was also observed in the yield of microsomal, but not nuclear membrane, protein mass as a function of thyroxine treatment. Prolonged thyroxine treatment (12 days) resulted in approximately 50% decreases in tadpole liver homogenate and microsomal NADH-cytochrome c reductase specific activities; in contrast, mitochondrial and nuclear membrane NADH-cytochrome c reductase specific activities were not altered under the same conditions. In addition, homogenate and microsomal NADPH-cytochrome c reductase specific activities were found to have increased significantly after 12 days of thyroxine treatment; however, the specific activity of NADPH-cytochrome c reductase in the mitochondrial fraction was unchanged. It was also observed that thyroxine treatment resulted in increases in homogenate and microsomal glucose-6-phosphatase specific activities, whereas the mitochondrial as well as nuclear membrane glucose-6-phosphatase specific activities remained unchanged. Furthermore, in contrast to homogenate and mitochondrial monoamine oxidase specific activities, which decreased 30 and 40%, respectively, as a consequence of thyroxine treatment (12 days), the succinate-cytochrome c reductase and oligomycin-sensitive Mg2+ ATPase specific activities determined for these fractions increased significantly. In all instances, changes as a result of thyroxine treatment in membrane-localized homogenate or organelle enzyme specific activities were apparent only after a 3- to 4-day initial latent period. The in vitro effects of thyroxine (10(-10) - 10(-5) M) on the membrane-localized enzyme activities examined in this study were either negligible or, as in the case of mitochondrial succinate-cytochrome c reductase and microsomal NADH-cytochrome c reductase, opposite to the changes observed in response to in vivo thyroxine treatment, with the exception of microsomal NADPH-cytochrome c reductase activity which was enhanced approximately 2-fold by 10(-5) M thyroxine...
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PMID:Alterations in enzyme and cytochrome profiles of Rana catesbeiana liver organelles during thyroxine-induced metamorphosis. Changes in membrane-localized phosphohydrolases, oxidoreductases, and cytochrome levels in response to in vivo thyroxine administration. 18 3

The transverse distribution of enzyme proteins and phospholipids within microsomal membranes was studied by analyzing membrane composition after treatment with proteases and phospholipases. Upon trypsin treatment of closed microsomal vesicles, NADH- and NADPH-cytochrome c reductases as well as cytochrome b5 were solubilized or inactivated, while cytochrome P-450 was partially inactivated. When microsomes were exposed to a concentration of deoxycholate which makes them permeable to macromolecules but does not disrupt the membrane, the detergent alone was sufficient to release four enzymes: nucleoside diphosphatase, esterase, beta-glucuronidase, and a portion of the DT-diaphorase. Introduction of trypsin into the vesicle lumen inactivated glucose-6-phosphatase completely and cytochrome P-450 partially. The rest of this cytochrome, ATPase, AMPase, UDP-glucuronyltransferase, and the remaining 50% of DT-diaphorase activity were not affected by proteolysis from either side of the membrane. Phospholipase A treatment of intact microsomes in the presence of albumin hydrolyzed all of the phosphatidylethanolamine, phosphatidylserine, and 55% of the phosphatidylcholine. From this observation, it was concluded that these lipids are localized in the outer half of the bilayer of the microsomal membrane; Phosphatidylinositol, 45% of the phosphatidylcholine, and sphingomyelin are tentatively assigned to the inner half of this bilayer. It appears that the various enzyme proteins and phospholipids of the microsomal membrane display an asymmetric distribution in the transverse plane.
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PMID:Enzyme and phospholipid asymmetry in liver microsomal membranes. 19 Feb 41

Light Golgi fractions (GF(1+2)) prepared from rat liver homogenates by a modification of the Ehrenreich et al. procedure (J. Cell Biol. 59:45) had significant NADPH-cytochrome P(450) reductase (NADPH-cyt c reductase) activity if assayed immediately after their isolation. An antibody raised in rabbits against purified microsomal and Golgi fractions. To find out whether this activity is located in bona fide Golgi elements or in contaminating microsomal vesicles, we used the following 3-step immunoadsorption procedure: (a) antirabbit IgG (raised in goats) was conjugated to small (2-5 mum) polycrylamide (PA) beads; (b) rabbit anti NADPH-cyt c reductase was immunoadsorbed to the antibody-coated beads; and (c) GF(1+2) was reacted with the beads carrying the two successive layers of antibodies. The beads were then recovered by centrifugation, and were washed, fixed, embedded in agarose, and processed for transmission electromicroscopy. Antireductase- coated beads absorbed 60 percent of the NADPH-cyt c reductase (and comparable fractions of NADH-cyt c reductase and glucose-6-phosphatase) but only 20 percent of the galactosyltransferase activity of the input GF(1+2). Differential vesicle counts showed that approximately 72 percent of the immunoadsorbed vesicles were morphologically recognizable Golgi elements (vesicles with very low density lipoprotein [VLDL] clusters or Golgi cisternae); vesicles with single VLDL and smooth surfaced microsome-like vesicles were too few (approximately 25 percent) to account for the activity. It is concluded that NADPH-cytochrome P(450) reductase is a Golgi membrane enzyme of probably uneven distribution among the elements of the Golgi complex.
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PMID:Presence of NADPH-cytochrome P-450 reductase in rat liver Golgi membranes. Evidence obtained by immunoadsorption method. 21 51

The effects of vitamin E deficiency on membrane integrity were studied by examining the temperature dependence of membrane-bound enzyme activities in liver mitochondria and microsome and in muscle sarcoplasmic reticulum. In vitamin E-deficient rabbits, the specific activities at 37 degrees of mitochondrial oligomycin-sensitive ATPase (EC 3.6.1.3), beta-hydroxybutyrate dehydrogenase (EC 1.1.1.30), and microsomal glucose-6-phosphatase (EC 3.1.3.9) were increased, whereas those of microsomal NADH cytochrome C reductase (EC 1.6.99.3) and sarcoplasmic reticulum Ca-ATPase were reduced in comparison to control rabbits. Arrhenius plots of activity against temperature yielded a linear plot over the range 10 to 40 degrees in the case of beta-hydroxybutyrate dehydrogenase, NADH cytochrome C reductase and Ca-ATPase, and multiple discontinuities for glucose-6-phosphatase and oligomycin-sensitive ATPase. In control rabbits, all five enzymes showed a single discontinuity in the Arrhenius plot over the range 16 to 19 degrees. These results reflect changes in the microenvironment of membrane-bound enzymes as a consequence of vitamin E depletion.
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PMID:Effects of vitamin E deficiency on the activities of lipid-requiring enzymes in rabbit liver and muscle. 22 Mar 97

Experiments were performed to localize the hepatic microsomal enzymes of phosphatidylcholine, phosphatidylethanolamine, and triacylglycerol biosynthesis to the cytoplasmic or lumenal surface of microsomal vesicles. Greater than 90 percent of the activities of fatty acid-CoA ligase (EC 6.2.1.3), sn-glycerol 3-phosphate acyltransferase (EC 2.3.1.15), lysophosphatidic acid acyltransferase, diacylglycerol acyltransferase (EC 2.3.1.20), diacylglycerol cholinephosphotransferase (EC 2.7.8.2), and diacylglycerol ethanolaminephosphotransferase (EC 2.7.8.1) was inactivated by proteolysis of intact microsomal vesicles. The phosphatidic acid phosphatase (EC 3.1.3.4) was not inactivated by any of the protease tested. Under conditions employed, <5 percent of the luminal mannose-6-phosphatase (EC 3.1.3.9) activity was lost. After microsomal integrity was disrupted with detergents, protease treatment resulted in a loss of >74 percent of the mannose-6-phosphatase activity. The latency of the mannose-6-phosphatase activity was not affected by protease treatment. Mannose-6-phosphatase latency was not decreased by the presence of the assay components of several of the lipid biosynthetic activities, indicating that those components did not disrupt the microsomal vesicles. None of the lipid biosynthetic activities appeared latent. The presence of a protease-sensitive component of these biosynthetic activities on the cytoplasmic surface of microsomal vesicles, and the absence of latency for any of these biosynthetic activities suggest that the biosynthesis of phosphatidylcholine, phosphatidylethanolamine, and triacylglycerol occurs asymmetrically on the cytoplasmic surface of the endoplasmic reticulum. The location of biosynthetic activities within the transverse plane of the endoplasmic reticulum is of particular interest for enzymes whose products may be either secreted or retained within the cell. Phosphatidylcholine, phosphatidylethanolamine, and triacylglycerol account for the vast majority of hepatic glycerolipid biosynthesis. The phospholipids are utilized for hepatic membrane biogenesis and for the formation of lipoproteins, and the triacylglycerols are incorporated into lipoproteins or accumulate within the hepatocyte in certain disease states (14). The enzymes responsible for the biosynthesis of these glycerolipids (Scheme I) from fatty acids and glycerol-3P have all been localized to the microsomal subcellular fraction (12, 16, 29, 30). Microsomes are derived from the endoplasmic reticulum and are sealed vesicles which maintain proper sidedness. (11, 22). The external surface of these vesicles corresponds to the cytoplasmic surface of the endoplasmic reticulum. Macromolecules destined for secretion must pass into the lumen of the endoplasmic reticulum (5, 23). Uncharged molecules of up to approximately 600 daltons are able to enter the lumen of rat liver microsomes, but macromolecules and charged molecules of low molecular weight do not cross the vesicle membrane (10, 11). Because proteases neither cross the microsomal membrane nor destroy the permeability barrier of the microsomal vesicles, only the enzymes and proteins located on the cytoplasmic surface of microsomal vesicles are susceptible to proteolysis unless membrane integrity is disrupted (10, 11). By use of this approach, several enzymes and proteins have been localized in the transverse plane of microsomal membranes (11). With the possible exception of cytochrome P 450, all of the enzymes and proteins investigated were localized asymmetrically by the proteolysis technique (11). By studies of this type, as well as by product localization, glucose-6-phosphate (EC 3.1.3.9) has been localized to the luminal surface of microsomal vesicles (11) and of the endoplasmic reticulum (18, 19). All microsomal vesicles contain glucose-6-phosphatase (18, 19) which can effectively utilize mannose-6-P as a substrate, provided the permeability barrier of the vesicles has been disrupted to allow the substrate access to the active site located on the lumenal surface (4). An exact correspondence between mannose- 6-phosphate activity and membrane permeability to EDTA has been established (4). The latency of mannose-6-phosphatase activity provides a quantitative index of microsomal integrity (4.) Few of the microsomal enzymes in the synthesis of phosphatidylcholine, phosphatidylethanolamine, and triacylglycerol have been solubilized and/or purified, and little is known about the topography of these enzymes in the transverse or lateral planes of the endoplasmic reticulum. An asymmetric location of these biosynthetic enzymes on the cytoplasmic or lumenal surface of microsomal vesicles may provide a mechanism for regulation of the glycerolipids to be retained or secreted by the cell, and for the biogenesis of asymmetric phospholipid bilayers. In this paper, we report investigations on the localization of all seven microsomal enzymes (Scheme I) in the biosynthesis of triacylglycerol, phosphatidylcholine, and phosphatidylethanolamine, using the protease technique with mannose-6-phosphatase serving as luminal control activity. The latency of these lipid biosynthetic enzymes was also investigated, using the latency of mannose-6-phosphatase as an index of microsomal integrity.
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PMID:Evidence that biosynthesis of phosphatidylethanolamine, phosphatidylcholine, and triacylglycerol occurs on the cytoplasmic side of microsomal vesicles. 61 95

Rat liver endoplasmic reticulum has been separated into four ribosome-containing subfractions, two from rapidly sedimentation endoplasmic reticulum and two from the microsomes, by differential centrifugation and sucrose density centrifugation. Ribosomes from one of the rapidly sedimenting subfractions were extracted by Trion X-100 as a complex with cytochrome P-450, optimally at a detergent protein ratio of 2/1 (w/w). Upon extraction approximately 50% of the cytochrome P-450 in the membrane appeared complex-bound to ribosomes, and, maximally, 6-7 subunit molecules of the cytochrome were attached per ribosome. The specific concentration of cytochrome P-450 on these ribosomes was 2.5-times higher than in the parent membrane. Cytochrome b5, glucose-6-phosphatase, NADPH-cytochrome c reductase, NADH-ferricyanide reductase, cytochrome oxidase and phospholipids were present in small or trace amounts on the ribosomes in relation to cytochrome P-450. Ribosomes extracted from other subfractions contained much less bound cytochrome P-450. Phenobarbital treatment induced an increase in the cytochrome P-450 content that was different for the various subfractions. This increase could not be correlated with changes in the amounts of cytochrome-ribosome complexes released by detergent. We propose that cytochrome P-450 is part of a specific binding site in the membrane for a fraction of the ribosomes attached to the endoplasmic reticulum. The ribosomes may be anchored to cytochrome P-450 via nascent chain proteins.
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PMID:On the involvement of cytochrome P-450 in the binding of ribosomes to a subfraction of rat-liver rapidly sedimenting endoplasmic reticulum. 83 30

The interaction between amphetamine and synthetic oral contraceptive steroids have been studied in the female rat. A progestational agent, quingestanol acetate, and a standard combination contraceptive (quingestanol acetate/ethynyl estradiol) were given with and without the concurrent administration of amphetamine. Steroid treatments increased the activity of some drug-metabolizing enzymes (aminopyrine N-demethylase, coumarin 3- hydroxylase, hexobarbital oxidase). Other parameters measured remained unaltered (glucose-6-phosphatase, aniline hydroxylase, cytochrome c reductase, cytochrome P 450, microsomal protein and phospholipid contents). Amphetamine treatment alone raised some drug-metabolizing enzymes (coumarin 3-hydroxylase, hexobarbital oxidase), increased microsomal phospholipid content and de novo synthesis, but elicited no effect on other enzymes measured. Amphetamine and quingestanol acetate given together significantly increased some drug metabolizing enzymes while the simultaneous treatment with combined steroids and amphetamine showed the most pronounced action. These experiments thus revealed that at least in the liver of the female rat, amphetamine elicited no overt hepatotoxicity, rather, brought about a weak inductive action of drug metabolizing enzymes. The application of steroid hormones also raised drug metabolism and the interaction between amphetamine and contraceptive steroids showed additive effects.
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PMID:Influence of oral contraceptives on the acute effect of amphetamine on the hepatic endoplasmic reticulum of the rat. 84 78


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