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:1.6.99.3 (diaphorase)
5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

With the aim of studying the mechanism behind the effect of estramustine in the treatment of prostatic carcinoma, the intracellular fate of the drug has been investigated in rat ventral prostate in vitro. Minced tissue was incubated with [3H] estramustine under different conditions, homogenized, and submitted to isopycnic centrifugation on a sucrose gradient using the recently introduced vertical tube rotor. The subcellular localization of the drug was determined by comparison between the distribution of radioactivity in the gradient fractions and the activities of a number of marker enzymes. No metabolism of estramustine occurred as judged by thin-layer chromatography. After incubation of the minced prostate tissue for 1 hour at 30 degrees C with 0.15 microM of [3H] estramustine, most of the drug was recovered in the cytosol fractions which also contained the highest concentrations of the estramustine-binding protein. However, after incubation with 220 microM of estramustine, most drug equilibrated in heavier fractions with high concentrations of N-acetyl-beta-glucosaminidase and cathepsin B, marker enzymes for the lysosomes as well as NADPH:cytochrome c reductase, marker enzyme for the endoplasmic reticulum. Extending the incubation time and increasing the temperature reduced the amount of estramustine equilibrating in the heavy fractions and concomitantly increased the portion localized in the cytosol. During all incubation conditions, very little drug seemed to accumulate in the nuclei since the drug distribution was completely different from that of DNA. This suggests that effects other than interaction with nuclear DNA might be of importance for the cytotoxic effect of estramustine.
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PMID:Intracellular localization of estramustine in rat ventral prostate in vitro. 679 11

Male 3-month-old Wistar rats dosed i.p. with 200 mg/kg of nitromethane or -ethane showed increased acid proteinase activity in the brain 4 h after the injection. The change was accompanied by a marginal increase in the cerebral glutathione concentration. Nitroethane caused enhanced epoxide hydrolase and UDP-glucuronosyltransferase activity in the hepatic microsomal fraction up to 48 h while 7-ethoxycoumarin o-deethylase decreased. These biochemical changes were accompanied by proliferation of smooth endoplasmic reticulum and degranulation and disorganization of the rough endoplasmic reticulum of the nitroethane-exposed liver cells. The hepatic effects of nitromethane were restricted to decreased cytochrome c reductase activity with proliferation of smooth endoplasmic reticulum. The results point at limited peroxidative damage possibly involving reduction of the nitrogroup.
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PMID:Comparison of acute toxic effects of intraperitoneally injected nitromethane and nitroethane in rats. 681 33

The rate of NADH oxidation with oxygen as the acceptor is very low in mouse liver plasma membrane and erythrocyte membrane. When vanadate is added, this rate is stimulated 10- to 20-fold. The absorption spectrum of vanadate does not change with the disappearance of NADH. The reaction is inhibited by superoxide dismutase, and there is no activity under an argon atmosphere. This indicates that oxygen is the electron acceptor and the reaction is mediated by superoxide. The vanadate stimulation is not limited to plasma membrane. Golgi apparatus and endoplasmic reticulum show similar increase in NADH oxidase activity when vanadate is added. The endomembranes have significant vanadate-stimulated activity with both NADH and NADPH. The vanadate-stimulated NADH oxidase in plasma membrane is inhibited by compounds, which inhibit NADH dehydrogenase activity: catechols, anthracycline drugs and manganese. This activity is stimulated by high phosphate and sulfate anion concentrations.
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PMID:Vanadate-stimulated NADH oxidation in plasma membrane. 691 71

Developing pea (Pisum sativum L.) cotyledons were labeled with radioactive amino acids, glucosamine, and mannose in pulse an pulse-chase experiments to study the synthesis, glycosylation, and transport of the reserve proteins vicilin and legumin to the protein bodies. Tissue extracts were fractionated on sucrose gradients to isolate either the endoplasmic reticulum (ER) or the protein bodies. Immunoaffinity gels were used to determine radioactivity in the reserve proteins (legumin and vicilin). After pulse-labeling for 45 min with amino acids, about half the total incorporated radioactivity coincided closely with the position of the ER marker enzyme NADH-cytochrome c reductase at a density of 1.13 g . cm-3 on the sucrose gradient. Both radioactivity and enzyme activity shifted to a density of 1.18 g . cm-3 in the presence of 3 mM MgCl2 indicating that the radioactive proteins were associated with the rough ER. Approximately half of the incorporated radioactivity associated with the rough ER was in newly synthesized reserve protein and this accounted for 80% of the reserve protein synthesized in 45 min. Trypsin digestion experiments indicated that these proteins were sequestered within the ER. In pulse-chase experiments, the reserve proteins in the ER became radioactive without appreciable lag and radioactivity chased out of the ER with a half-life of 90 min. Radioactive reserve proteins became associated with a protein body-rich fraction 20-30 min after their synthesis and sequestration by the ER. Pulse-chase experiments with radioactive glucosamine and mannose in the presence and absence of tunicamycin indicated that glycosylation of vicilin occurs in the ER. However, glycosylation is not a prerequisite for transport of vicilin from ER to protein bodies. Examination of the reserve protein polypeptides by SDS PAGE followed by fluorography showed that isolated ER contained legumin precursors (Mr 60,000-65,000) but not the polypeptides present in mature legumin (Mr 40,000 and 19,000) as well as the higher molecular weight polypeptides of vicilin (Mr 75,000, 70,000, 50,000, and 49,000). The smaller polypeptides of vicilin present in vicilin extracted from protein bodies (Mr 12,000-34,000) were absent from the ER. The results show that newly synthesized reserve proteins are preferentially and transiently sequestered within the ER before they move to the protein bodies, and that the ER is the site of storage protein glycosylation.
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PMID:Role of the endoplasmic reticulum in the synthesis of reserve proteins and the kinetics of their transport to protein bodies in developing pea cotyledons. 706 59

Studies have been made of the morphology, enzyme activity and protein composition of liver endoplasmic reticulum in rats exposed to acute doses of the carcinogen, 2-acetylaminofluorene (2-AAF). Electron microscopic examination revealed numerous ultrastructural changes in the hepatocyte; most consistent alterations were the disorganisation of endoplasmic reticulum system with apparent increase of smooth endoplasmic reticulum. Administration of 2-AAF to rats immediately depressed microsomal glucose-6-phosphatase activity and eventually induced epoxide hydratase activity 6--7-fold over control activity. The induction was time-dependent and maximal rates of induction were observed at dosages greater than 40 mg/kg body wt. The treatment also induced cytochrome b5 content, NADH and NADPH cytochrome c reductase activities (1.0--1.5-fold). Only very small changes in the total content of cytochrome P-45- were noted. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of microsomal proteins from 2-AAF pretreated animals showed time-dependent induction of two polypeptides which differed slightly in migration, in the region of Mr = 48000; the fast-migrating induced polypeptide has been identified as epoxide hydratase. Two-dimensional PAGE analysis of microsomal proteins from 2-AAF exposed rats showed a reproducible deletion of a protein with molecular weight in the region of 67000. The basis for the alterations in the protein composition of endoplasmic reticulum in response to 2-AAF treatment is discussed.
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PMID:Alterations in the enzyme activity and polypeptide composition of rat hepatic endoplasmic reticulum during acute exposure to 2-acetylaminofluorene. 707 8

Plasma membranes, contaminated very little by endoplasmic reticulum elements, were isolated from rat liver. Activities of NADH-oxidoreductase and b-type cytochromes were higher than expected from this contamination. Between 50 and 80% of these activities were endogenous to plasma membrane. A similar result was obtained after refractionation of digitonin-treated plasma membranes on a sucrose density gradient. This is further evidence for the localization of NADH-ferricyanide reductase, NADH-cytochrome c reductase, and cytochromes b5, P450 and P420 in liver cell membranes.
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PMID:Density gradient fractionation of digitonin-treated rat liver plasma membranes and subcellular localization of NADH-oxidoreductase and B-type cytochromes. 710 80

1. Lantana intoxication of guinea-pig caused a decrease in hepatic microsomal protein content, the phospholipid: protein ratio, and the cholesterol: protein ratio. 2. Activities of aniline hydroxylase, aminopyrine N-demethylase, NADH-cytochrome c reductase, NADH-ferricyanide reductase, UDP-glucuronosyl transferase, cytochrome P-450 and glucose 6-phosphatase were decreased. 3. Activities of Mg2+ -ATPase and Na+ -K+ -ATPase were increased. However, activities of 5-nucleotides and NADPH-cytochrome c reductase were unaffected. 4. The liver endoplasmic reticulum is an important target organelle during lantana poisoning of guinea-pigs.
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PMID:Biochemical changes in hepatic microsomes of guinea-pig under lantana toxicity. 711 63

Rapidly sedimenting endoplasmic reticulum (RSER), which is known to be a complex between endoplasmic reticulum and mitochondria, was isolated from rat liver and purified through a sucrose density gradient by centrifugation according to a well established procedure previously published by G. C. Shore and J. R. Tata. This complex was characterized by microsomal (NADPH-cytochrome c reductase) and mitochondrial (succinate-cytochrome c reductase and NADP-isocitrate dehydrogenase) marker enzymes and was examined for the ability to synthesize microsomal lipids and mitochondrial polyglycerophosphatides. Results of these experiments showed that the RSER is capable of synthesizing key microsomal lipids, i.e., phosphatidic acid, phosphatidylcholine, and neutral lipids, as well as mitochondrial phosphatidylglycerosphate and phosphatidic acid, phosphatidylcholine, and neutral lipids, as well as mitochondrial phosphatidylglycerophosphate and phosphatidylglycerol. Furthermore, the level of synthesis of these lipids paralleled the level of activity of microsomal and mitochondrial marker enzymes found in the RSER preparation. Details of these experimental findings and some implications are discussed in view of the possible functional role of RSER.
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PMID:Biosynthesis of microsomal phospholipids and mitochondrial polyglycerophosphatides in rapidly sedimenting endoplasmic reticulum. 717 97

Male Wistar rats were exposed to 200, 1000 or 2000 ppm of 1,1,2-trichloro-1,2,2-trifluoroethane vapor 5 days a week 6 h daily for 1 or 2 weeks. Proliferation and vacuolisation of the smooth endoplasmic reticulum (SER) of the liver was seen electron microscopically after 1 and 2 weeks in the rats exposed to 1000 and 2000 ppm. Among the hepatic drug metabolizing enzymes, NADPH cytochrome c reductase activity showed a dose-related decrease whereas the tightly membrane-bound UDPglucuronosyltransferase exhibited a dose-dependent enhancement in its measurable activity. The overall drug oxidation reaction, 7-ethoxycoumarin O-deethylase was not affected by the 1,1,2-trichloro-1,2,2,-trifluoroethane inhalation at all, either in the liver or in the kidneys. 1,1,2-Trichloro-1,2,2-trifluoroethane binds to cytochrome P-450 with the production of a type I difference spectrum, suggesting that it may act as a substrate for this enzyme. The binding affinity is increased by phenobarbital-treatment of the rats.
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PMID:Dose-related hepatotoxicity of 1,1,2-trichloro-1,2,2-trifluoroethane in short-term intermittent inhalation exposure in rats. 721 20

In this paper, evidence is presented on the capacity of Ehrlich ascites cells to synthesize in vitro monounsaturated fatty acids from radioactive palmitate. Localization of the double bond was determined by ozonolysis and subsequent reduction of the ozonides to aldesters followed by gas liquid chromatography. These results proved that Ehrlich ascites cells have a delta 9 desaturase that catalyzes the biosynthesis of palmitoleic acid from palmitic acid and oleic and vaccenic acid via elongation-desaturation and desaturation-elongation, respectively, using palmitic acid as substrate. Furthermore, it is shown that, as in the hepatic cells, delta 9 desaturase enzyme activity of the tumoral cells is associated with the endoplasmic reticulum. The electron transport components involved in the desaturase system, i.e., NADH-cytochrome b5 reductase and NADH-cytochrome c reductase, were also measured. The activities of these enzymes do not appear to be rate-limiting in the desaturase activity of these tumoral cells.
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PMID:In vitro conversion of saturated to monounsaturated fatty acid by Ehrlich ascites cells. 732 10


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