Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.5.2 (NQO1)
 6,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytochrome oxidase (CCO), peroxidase, succinic dehydrogenase (SDG) and NADH-diaphorase were studied electron-cytochemically in leprous macrophages (LM) of granulomas of patients suffering from lepromatous leprosy. The LM peroxidase activity and location differed, this affecting the completeness of M. leprae phagocytosis. High CCO activity in LM cytoplasm was not a factor essentially influencing M. leprae disintegration. SDG and NADH-diaphorase, locating predominantly in membraneous structures of M. leprae, show low activity in LM cytoplasm.
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PMID:[Evaluation of the functional state of the leprous macrophages]. 285 35

Thyrocytes isolated from porcine thyroids by mechanical and enzymatic dispersion and cultured in Eagle's minimal essential medium, supplemented with 5% (v/v) fetal calf serum, glutamine and cortisol, formed a continuous monolayer within 48 h. This monolayer was without cytochemical peroxidase and diaphorase (NADPH reoxidation) activity. In the presence of bovine thyrotrophin (bTSH; 50 mu./l) the cells developed a follicular-like architecture which was maximal at 4 days before reverting back to a uniform monolayer at 6 days. There were no detectable changes in the total DNA content over this period. The follicular structures had marked diaphorase and peroxidase activity, the latter being apically distributed. Concomitant with follicle formation bTSH induced uptake and organification of iodide presented to the cells during the last 6 h of culture. The extent of this process depended on the dose of bTSH and the duration of stimulation. The most sensitive effects for both iodide uptake and organification occurred with 1 mu. bTSH/l and were maximal with 100 mu./l. Uptake and organification were increased 20 +/- 8-fold and 9.6 +/- 2-fold (n = 10) respectively over the control with 100 mu./l and the doses of bTSH at which a half maximal response was seen (ED50) were 15 +/- 2 and 7 +/- 1 (S.D) mu./l (n = 10) respectively. On changing the culture medium to a serum-free system using HB101 culture medium the stimulation time for the most sensitive bTSH effect was reduced to 2.5 days.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Measurement of low concentrations of bovine thyrotrophin by iodide uptake and organification in porcine thyrocytes. 299 9

This communication presents the results obtained in tubular aggregates of 24 enzyme histochemical techniques for demonstrating activity of oxidoreductases, transferases, hydrolases and isomerases. The activity characteristics of the tubular aggregates in m. gluteus medius of 18 patients with diseases of the neuromuscular system were almost identical. A high activity of the mitochondrial enzymes, NADPH: tetrazolium oxidoreductase, NADH:tetrazolium oxidoreductase and cytochrome c oxidase, could be shown in the pathological structures, whereas the activity of the mitochondrial enzymes, glycerol-3-phosphate:menadione oxidoreductase, succinate:PMS oxidoreductase, malate:NAD+ oxidoreductase and isocitrate:NAD+ oxidoreductase, and the partial mitochondrial enzymes, malate:NADP+ oxidoreductase and isocitrate:NADP+ oxidoreductase, was very slight or even absent. There was a moderate to strong activity of the glycolytic enzymes lactate:NAD+ oxidoreductase, glyceraldehyde-3-phosphate:NAD+ oxidoreductase, phosphofructokinase, phosphoglucomutase and glucose phosphate isomerase. In contrast, the activity of alpha-glucan phosphorylase was slight. The activity of phosphogluconate:NADP+ oxidoreductase, glucose-6-phosphate:NADP+ oxidoreductase and 5'-nucleotidase was slight, whereas there was no activity of myosin ATPase and mitochondrial ATPase, acid phosphatase or alkaline phosphatase. The high activity of AMP-deaminase was very striking. The activity of peroxidase was moderate. Results obtained with adsorption studies point to adsorption of some of the enzymes studied to the tubular aggregates in vivo and this phenomenon very probably determined the histochemical characteristics of these structures.
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PMID:Histochemical features of tubular aggregates in diseased human skeletal muscle fibres. 317 98

The interaction of N-(4-ethoxyphenyl)p-benzoquinone imine (NEPBQI), a metabolite formed during peroxidase catalyzed metabolism of p-phenetidine, with GSH and its effects in isolated rat hepatocytes were investigated. When reacted with GSH NEPBQI formed both a mono- and a diglutathione conjugate as well as GSSG. Formation of glutathione conjugates and GSSG also occurred when NEPBQI was added to isolated hepatocytes. The formation of GSSG was, however, only detectable if the hepatocytes had been pretreated with the GSSG reductase inhibitor BCNU (1,3-bis-(2-chloroethyl-1-nitrosourea). Similarly, NEPBQI caused a rapid decrease in cellular free protein thiols when added to hepatocytes, however this was expressed at higher concentrations than for effects on GSH. The protein thiol decrease was correlated with protein binding of NEPBQI. NEPBQI was also shown to be toxic to isolated hepatocytes. At a concentration of 400 microM extensive bleb formation was followed by loss of cell membrane integrity and cell death. To assess further the subcellular metabolism of NEPBQI microsomes and cytosol was used. NEPBQI was found to be preferentially reduced by cytochrome P-450 reductase in the microsomes whereas DT-diaphorase catalyzed its reduction in cytosol. NEPBQI did not undergo significant redox cycling since no formation of O2 was observed. Thus, the cytotoxic effect of NEPBQI appears to be due to protein arylation rather than redox cycling.
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PMID:Cellular effects of N(4-ethoxyphenyl)p-benzoquinone imine, a p-phenetidine metabolite formed during peroxidase reactions. 379 94

Streptococcus sanguis, whose growth appears to be independent of the availability of iron, makes no hemes, contains neither catalase nor peroxidase, and can accumulate millimolar concentration levels of H2O2 during aerobic growth. It possesses a single manganese-containing superoxide dismutase whose concentration can be varied over a 50-100-fold range by manipulating the availability of oxygen during growth. Cell extracts contain a soluble NADH-plumbagin diaphorase which mediates O2- production in vitro and presumably also in vivo. Plumbagin increased oxygen consumption by S. sanguis and imposed an oxygen-dependent toxicity. Cells grown aerobically and containing elevated levels of superoxide dismutase were resistant to this toxicity. Dimethyl sulfoxide, which was shown to permeate S. sanguis freely, was used as an indicating scavenger of OH. An in vitro enzymic source of O2- plus H2O2 generated formaldehyde from dimethyl sulfoxide, an indication of OH. production. Either superoxide dismutase or catalase inhibited this OH. production and iron salts augmented it. Intact, aerobic cells of S. sanguis also gave evidence of OH. production, in the presence of plumbagin, but all of it appeared to be generated outside the cells. In addition, 0.5 M dimethyl sulfoxide did not diminish the oxygen-dependent toxicity of plumbagin. We conclude that, in S. sanguis, O2- can exert a toxic effect independent of the production of OH..
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PMID:Oxygen toxicity in Streptococcus sanguis. The relative importance of superoxide and hydroxyl radicals. 627 24

A membrane-associated b-type cytochrome (a proposed component in the neutrophil microbicidal superoxide generating system) has been partially purified from nonactivated beef granulocytes to a specific heme content of 20 nmol of heme/mg of protein, a value about 10-fold higher than those previously reported. The hemoprotein was solubilized at low temperature (4 degrees C) from mixed granule (30,000 X g) cell fractions using Triton X-114 detergent. Warming the extract to 25 degrees C allowed separation into detergent and aqueous phases; cytochrome b558 partitioned exclusively into the detergent phase, allowing separation from other visible-absorbing species (e.g. myeloperoxidase) and indicated an intrinsic membrane localization (Bordier, C. (1981) J. Biol. Chem. 256, 1604-1607). The partitioned cytochrome was chromatographed on hydroxylapatite and a hydrophobic affinity matrix, allowing a 185-fold (heme content) purification from the granule extract. The cytochrome preparation revealed three equal-staining protein bands by sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis; apparent molecular weights were 14,000, 12,000, and 11,000. The question of heterogeneity of the preparation versus subunit structure is not resolved at present. The hemoprotein binds carbon monoxide, consistent with a proposed role as a terminal oxidase, and has an unusually negative oxidation-reduction potential (-225 mV) similar to that observed in granulocyte membranes. The preparation is devoid of NAD(P)H-diaphorase and cytochrome c reductase activities.
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PMID:Cytochrome b558 from (bovine) granulocytes. Partial purification from Triton X-114 extracts and properties of the isolated cytochrome. 643 85

The role of various enzymes and biological molecules on the activation and deactivation of the metabolites of phenol was investigated in vitro. Phenol, the major metabolite of benzene, is metabolized to hydroquinone and catechol. Activation of these metabolites and deactivation of their oxidized forms was assessed by the amount of covalent binding to microsomal protein. [14C]Phenol and NADPH were incubated with hepatic microsomes isolated from phenobarbital-pretreated guinea pigs, and 2.33 nmoles of hydroquinone and 0.12 nmole of catechol were formed per minute per milligram of microsomal protein. Covalent binding of the metabolites to microsomal protein incubated with microsomes isolated from guinea pigs pretreated with phenobarbital was 252 pmoles bound/min/mg; with microsomes from untreated guinea pigs, covalent binding was 146 pmoles bound/min/mg. Covalent binding was inhibited greater than 90% with the addition of N-octylamine, ascorbate, or GSH. The addition of superoxide dismutase inhibited covalent binding with microsomes isolated from phenobarbital-pretreated guinea pigs 35% but did not inhibit it with microsomes isolated from untreated animals. Partially purified guinea pig hepatic DT-diaphorase [NAD(P)H (quinone acceptor) oxidoreductase, EC 1.6.99.2] inhibited covalent binding 70%. This effect was reversed in the presence of dicumarol, a specific inhibitor of DT-diaphorase. DT-diaphorase present in the 10(5) X g supernatant fraction was also active in inhibiting covalent binding but only after the removal of endogenous reduced glutathione. This effect could also be reversed by dicumarol. The addition of diaphorase (NADH:lipoamide oxidoreductase, EC 1.6.4.3) partially purified from Clostridium kluyveri inhibited covalent binding 86%. The addition of hydrogen peroxide and horseradish peroxidase (peroxidase, EC 1.11.17) or myeloperoxidase(s) increased covalent binding 30-fold and 6-fold, respectively. Ascorbate decreased this binding greater than 95%. These results indicate that hydroquinone, catechol, and phenol as well as their oxidized forms can be activated or deactivated by several of the above model systems. These systems may play a role in the myelotoxicity of benzene by modulating covalent binding.
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PMID:DT-diaphorase and peroxidase influence the covalent binding of the metabolites of phenol, the major metabolite of benzene. 674 27

In this study, we have characterized quinone reductase (QR), glutathione (GSH), glutathione S-transferase (GST) and their induction by a chemoprotector, 1,2-dithiole-3-thione (D3T), in the human myeloid cell lines ML-1 and HL-60. In addition, we also examined the toxicity of hydroquinone (HQ), a benzene metabolite, to these two cell lines. Both of the cell lines contain a basal level of cellular GSH, which is similar in the two cell lines. Although ML-1 cells contain much higher QR specific activity than HL-60 cells, which are relatively QR deficient, the GST specific activity of ML-1 cells is 1.8 times less than that of HL-60 cells. Immunoblot experiments showed that the GST in these two cell lines is GST pi. In addition, HL-60 cells exhibit 4.5 times more myeloperoxidase specific activity than ML-1 cells. Inclusion of D3T in the cultures could induce significant increases in cellular GSH content and QR activity, but not GST activity in either cell line. Treatment with HQ caused both inhibition of cell proliferation and loss of cell viability in these two myeloid cell lines. HQ treatment also resulted in a significant depletion of cellular GSH, which preceded the loss of cell viability. Pretreatment of both cell lines with buthionine sulfoximine, an inhibitor of GSH biosynthesis, markedly increased HQ-induced toxicity. In contrast, the presence of dicumarol, a QR inhibitor, failed to potentiate HQ-induced toxicity in ML-1 cells. On the other hand, pretreatment of these two myeloid cell lines with D3T significantly protected against HQ-induced inhibition of cell proliferation and cell death. Therefore, the above results suggest that GSH but not QR is an important factor involved in the toxicodynamics of HQ in these myeloid cells.
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PMID:Characterization of quinone reductase, glutathione and glutathione S-transferase in human myeloid cell lines: induction by 1,2-dithiole-3-thione and effects on hydroquinone-induced cytotoxicity. 751 Dec

We investigated the involvement of nitric oxide in trinitrobenzene-sulfonic acid (TNB) colitis. Every 24 h after TNB, rats were orally dosed with NG-nitro-L-arginine methyl ester (L-NAME; 30 mg/kg), NG-nitro-D-arginine methyl ester (D-NAME), or water, and food intake, body weight, and plasma nitrite levels were measured. On day 6, colonic nitric oxide synthase and myeloperoxidase (MPO) activity, histology, intestinal muscle growth, NADPH-diaphorase, and myenteric nerve function were assessed. Food intake and body weight were reduced during the first 72 h of colitis. On day 6 post-TNB, a fourfold increase in mucosal nitric oxide synthase, a 30-fold increase in MPO, and a fivefold elevation in plasma nitrite were measured. Smooth muscle hyperplasia and hypertrophy in both colonic muscle layers, numerous diaphorase-positive macrophages in the myenteric plexus, and a suppression of myenteric nerve function were also observed. Unlike D-NAME, oral L-NAME reduced MPO and intestinal muscle hyperplasia by > 90%. Likewise, plasma nitrite and colonic nitric oxide synthase were reduced by > 70%. L-NAME completely prevented macrophage infiltration into the muscle. Conversely, it had no effect on anorexia or intestinal smooth muscle hypertrophy, nor did it affect suppressed myenteric nerve neurotransmitter release. These results demonstrate the selective transmural protective effects of L-NAME in the inflamed colon, implicating nitric oxide as a mediator.
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PMID:The selective beneficial effects of nitric oxide inhibition in experimental colitis. 753 57

A study has been made of the distribution of nitric oxide synthase (NOS) in the developing avian ciliary ganglion. Nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) activity first appeared in ciliary neurones at embryonic day 10 (E10). The number of NADPH-d positive neurones appeared maximal at this age and thereafter declined; at post hatched day 4 (P4) these neurones were found predominately in the periphery of the ganglion. At the light microscope level the NADPH-d stain appeared throughout the cell soma of the ciliary neurones. This was confirmed using tissue culture techniques. Ultrastructural delineation of horseradish peroxidase-labelled NOS antibodies was also found in the calyx where it was bound to the membranes of the endoplasmic reticulum as well as to the outer membranes of mitochondria. This distribution of NOS in the soma and calyx is consistent with the physiological role of NO as a co-transmitter and retrograde messenger that regulates the quantal secretion of the principal transmitter, acetylcholine, from the calyx.
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PMID:Location of nitric oxide synthase in the developing avian ciliary ganglion. 753 72


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