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:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A ribonuclease with a molecular weight of 29 kDa as determined by FPLC-gel filtration on Superose 12 was isolated from the sclerotia of the mushroom Pleurotus tuber-regium using a procedure involving extraction with aqueous buffer, ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-cellulose, and FPLC on Mono S. The protein was unadsorbed on DEAE-cellulose but adsorbed on Affi-gel blue gel and CM-cellulose. It was homodimeric, made up of two identical subunits, each with a molecular weight of 14.5 kDa as witnessed in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It exhibited potent ribonucleolytic activity toward Poly G. Its ribonucleolytic activity was resistant to heating at 100 degreesC for 30 min, but was inhibited by HgCl2, ZnSO4, NiSO4, CaCl2, and Pb(NO3)2.
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PMID:A ribonuclease from sclerotia of the edible mushroom Pleurotus tuber-regium. 978 79

Nitric oxide (NO), constitutively produced by endothelial nitric oxide synthase (eNOS), plays a major role in the regulation of blood pressure and vascular tone. We generated transgenic mice overexpressing bovine eNOS in the vascular wall using murine preproendothelin-1 promoter. In transgenic lineages with three to eight transgene copies, bovine eNOS-specific mRNA, protein expression in the particulate fractions, and calcium-dependent NOS activity were confirmed by RNase protection assay, immunoblotting, and L-arginine/citrulline conversion. Immunohistochemical studies revealed that eNOS protein was predominantly localized in the endothelial cells of aorta, heart, and lung. Blood pressure was significantly lower in eNOS-overexpressing mice than in control littermates. In the transgenic aorta, basal NO release (estimated by Nomega-nitro-L-arginine-induced facilitation of the contraction by prostaglandin F2alpha) and basal cGMP levels (measured by enzyme immunoassay) were significantly increased. In contrast, relaxations of transgenic aorta in response to acetylcholine and sodium nitroprusside were significantly attenuated, and the reduced vascular reactivity was associated with reduced response of cGMP elevation to these agents as compared with control aortas. Thus, our novel mouse model of chronic eNOS overexpression demonstrates that, in addition to the essential role of eNOS in blood pressure regulation, tonic NO release by eNOS in the endothelium induces the reduced vascular reactivity to NO-mediated vasodilators, providing several insights into the pathogenesis of nitrate tolerance.
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PMID:Hypotension and reduced nitric oxide-elicited vasorelaxation in transgenic mice overexpressing endothelial nitric oxide synthase. 985 37

The goal of this study was to determine whether hypoxia alters expression of endothelial nitric oxide synthase (eNOS) in the systemic circulation. Rats breathed either air or 10% oxygen for 12 hours, 48 hours, or 7 days. Thoracic aortas were excised and either mounted in organ bath myographs or frozen in liquid nitrogen for later extraction of protein and RNA. eNOS protein (Western blotting) was decreased (20% of normoxic control) after 12 hours, 48 hours, and 7 days of hypoxia. eNOS mRNA (ribonuclease protection assay) was similarly reduced. Acetylcholine (10(-4) mol/L) reversed phenylephrine (10(-5) mol/L) preconstriction by 53.3+/-5.6% in aortic rings from normoxic rats and 26.1+/-4.8% in rings from rats exposed to hypoxia for 48 hours (P<0.05), with comparable impairment of relaxation by the calcium ionophore A23187 (10(-5) mol/L). Responses to diethylamine nitric oxide and 8-bromo-cGMP were unaffected. Aortic cGMP levels after incubation with acetylcholine (10(-6) mol/L) averaged 14.0+/-1.8 fmol/mg in rings from normoxic rats compared with 8.7+/-1.0 fmol/mg in rings from hypoxic rats (P<0. 05). Similarly, nitrate concentration (by capillary electrophoresis) in the media in which the rings were incubated was reduced in the hypoxic group (5.6+/-0.23 micromol/L for hypoxic rats and 7.8+/-0.7 micromol/L for normoxic rats). Impaired endothelial NO release may handicap the vascular responses that defend vital organ function during hypoxia.
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PMID:Downregulation of endothelial nitric oxide synthase in rat aorta after prolonged hypoxia in vivo. 1074 3

The current studies were undertaken to establish an in vitro cellular model to study the transport of SO and Cl(-) and hormonal regulation and to define the possible function of the downregulated in adenoma (DRA) gene. Utilizing a postconfluent Caco-2 cell line, we studied the OH(-) gradient-driven (35)SO and (36)Cl(-) uptake. Our findings consistent with the presence of an apical carrier-mediated (35)SO/OH(-) exchange process in Caco-2 cells include: 1) demonstration of saturation kinetics [Michaelis-Menten constant (K(m)) of 0.2 +/- 0.08 mM for SO and maximum velocity of 1.1 +/- 0.2 pmol x mg protein(-1) x 2 min(-1)]; 2) sensitivity to inhibition by DIDS (K(i) = 0.9 +/- 0.3 microM); and 3) competitive inhibition by oxalate and Cl(-) but not by nitrate and short chain fatty acids, with a higher K(i) (5.95 +/- 1 mM) for Cl(-) compared with oxalate (K(i) = 0.2 +/- 0.03 mM). Our results also suggested that the SO/OH(-) and Cl(-)/OH(-) exchange processes in Caco-2 cells are distinct based on the following: 1) the SO/OH(-) exchange was highly sensitive to inhibition by DIDS compared with Cl(-)/OH(-) exchange activity (K(i) for DIDS of 0.3 +/- 0.1 mM); 2) Cl(-) competitively inhibited the SO/OH(-) exchange activity with a high K(i) compared with the K(m) for SO, indicating a lower affinity for Cl(-); 3) DIDS competitively inhibited the Cl(-)/OH(-) exchange process, whereas it inhibited the SO/OH(-) exchange activity in a mixed-type manner; and 4) utilizing the RNase protection assay, our results showed that 24-h incubation with 100 nM of thyroxine significantly decreased the relative abundance of DRA mRNA along with the SO/OH(-) exchange activity but without any change in Cl(-)/OH(-) exchange process. In summary, these studies demonstrated the feasibility of utilizing Caco-2 cell line as a model to study the apical SO/OH(-) and Cl(-)/OH(-) exchange processes in the human intestine and indicated that the two transporters are distinct and that DRA may be predominantly a SO transporter with a capacity to transport Cl(-) as well.
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PMID:Sulfate and chloride transport in Caco-2 cells: differential regulation by thyroxine and the possible role of DRA gene. 1125 86

Cytokines play an important and complex role in the pathogenesis of systemic autoimmune diseases. In susceptible H-2s mice, inorganic mercury (Hg) induces lymphoproliferation, antinucleolar antibodies against the 34-kDa-protein fibrillarin, and systemic immune-complex (IC) deposits. Here, we report extensive analysis of cytokine mRNA levels in susceptible A.SW (H-2s) and resistant A.TL (H-2tl) mice under unstimulated conditions and during oral treatment with Hg and/or silver nitrate (Ag). Cytokine mRNA expression in lymphoid tissues was assessed using the ribonuclease protection assay and phosphorimaging. Baseline expression of IL-2 and IFN-gamma mRNA was higher in A.SW than in A.TL mice. In A.SW mice, Hg treatment caused early up-regulation of IL-2 and IFN-gamma levels, followed by substantial expression of IL-4 mRNA, which was significant compared to control A.SW and Hg-treated A.TL mice. Hg-exposed A.TL mice exhibited unchanged IFN-gamma, reduced IL-2 and greatly increased IL-10 mRNA expression. Ag-treated A.SW mice, which develop antifibrillarin antibodies (AFA) but exhibit minimal immune activation and no IC deposits, showed an early increase in IL-2 and IFN-gamma mRNA, but only a small and delayed rise in IL-4 mRNA. In conclusion, H-2-linked resistance to Hg-induced AFA is characterized by low constitutive expression of IL-2 and IFN-gamma mRNA, which is not increased by Hg, and a marked increase in IL-10 expression. Conversely, the key features of H-2-linked susceptibility to Hg- and Ag-induced AFA are up-regulation of IL-2, IFN-gamma and IL-4 mRNA expression, and down-regulation of IL-10 expression.
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PMID:Murine metal-induced systemic autoimmunity: baseline and stimulated cytokine mRNA expression in genetically susceptible and resistant strains. 1167 13

A number of previous studies have indirectly (electron paramagnetic resonance, nitrite/nitrate, ribonuclease protection assay for inducible nitric oxide synthase (iNOS) mRNA, l-citrulline assay) demonstrated the production of nitrogen monoxide (NO) during early cardiac allograft rejection. This study reports the first direct, quantitative measurement using an electrochemical method of NO produced from rejecting allograft tissue studied in vitro. A rat heterotopic abdominal transplant preparation was utilized. Day 7 isograft (ACI to ACI) or allograft (Lewis to ACI) transplanted hearts were atraumatically harvested and suspended at 4 degrees C in Ringers-Hepes solution. An electrochemical system highly sensitive and specific for NO consisting of a Nafion-coated platinum disk electrode (lower limit, 50 nM NO) coupled to an analysis system measured ongoing oxidation of NO. Measurements were carried out after inserting the electrode in the tissue block and warming the block to 25 degrees C. Additional measurements were also made after incubation of tissue with aminoguanidine (AG), a relatively selective iNOS inhibitor. Direct measurements (mean +/- SEM) from allograft tissue indicated a fourfold increase in NO as compared with isografts (13.41 +/- 4.40 microM NO vs. 3.43 +/- 2.04 microM NO). Incubation of allograft tissue with AG reduced NO levels to isograft levels (13.41 +/- 4.40 microM NO vs. 5.94 +/- 3.14 microM NO); AG had no effect on measured isograft NO levels. Direct, quantitative measurement of NO from tissue is feasible and reproducible, and discrimination between different levels of NO production can be made. These results confirm the imputed results from the previous studies using this experimental model. This technology promises to be a valuable tool for evaluating specific modulators of NO production studied under a variety of physiologic and pathophysiologic conditions.
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PMID:In situ measurement of nitric oxide production in cardiac isografts and rejecting allografts by an electrochemical method. 1173 Mar 63

[M+Ag]+ ions were produced by electrospray from neutral high-mannose, hybrid and complex N-linked glycans obtained from bovine ribonuclease, chicken egg glycoproteins, bovine fetuin and porcine thyroglobulin by the addition of silver nitrate to the electrospray solvent. Both singly and doubly charged ions were produced but, as the signals were split between the two silver isotopes, sensitivity was not as high as with the sodium adducts reported earlier. Collision-induced dissociation (CID) spectra were dominated by ions produced by glycosidic cleavages, mainly of the B- and Y-type. Internal cleavage ions involving both B and Y cleavages were very prominent but cross-ring fragments were generally of very low abundance or absent. Silver was very efficient at cleaving the glycosidic bonds, so much so that spectra tended to contain glycosidic ions at most possible combinations of the constituent monosaccharides.
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PMID:Ionization and fragmentation of N-linked glycans as silver adducts by electrospray mass spectrometry. 1565 98

Nitric oxide (NO) derived from endothelial NO synthase (eNOS) is a powerful vasodilator and possesses vasoprotective effects. Therefore, augmentation of eNOS expression and -activity by pharmacological means could provide protection against cardiovascular disease. However, this concept has been questioned recently, because in several disease models, eNOS upregulation was associated with a dysfunctional enzyme (referred to as eNOS uncoupling). In contrast, the present study demonstrates that an eNOS gene expression-enhancing compound with additional protein kinase C (PKC) inhibitory properties can upregulate eNOS while preserving its enzymatic function. Apolipoprotein E-knockout mice were treated for 7 days with midostaurin (4'-N-benzoyl staurosporine, compound CGP 41251, 50-125 mg/kg/day), a PKC inhibitor previously shown to increase eNOS expression and NO production in cultured human endothelial cells. Midostaurin treatment enhanced eNOS mRNA expression (RNase protection assay) in mouse aorta, kidney, and heart in a dose-dependent fashion. In the dorsal skinfold microcirculation, midostaurin produced an arteriolar vasorelaxation (intravital microscopy), which could be prevented by the NOS inhibitor L-NAME, indicating that the upregulated eNOS remained functional. In organ chamber experiments, the aorta from midostaurin-treated mice showed an enhanced NO-mediated relaxation in response to acetylcholine. Accordingly, serum levels of nitrite/nitrate (NO-Analyzer) were increased, and the production of reactive oxygen species in the aorta (L-012 chemiluminescence) was reduced by midostaurin. Thus, in mice in vivo, midostaurin treatment results in enhanced expression of eNOS with preserved enzyme function and enhanced production of bioactive NO. Given the beneficial effects of endothelial-derived NO, vasoprotective and anti-atherosclerotic effects are likely to ensue.
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PMID:Midostaurin upregulates eNOS gene expression and preserves eNOS function in the microcirculation of the mouse. 1589 May 50

Desiccation of 8- to 13-day-old seedlings, achieved by withholding nutrient solution from the vermiculite root medium, caused a reduction in nitrate reductase activity of the leaf tissue. Activity declined when leaf water potentials decreased below -2 bars and was 25% of the control at a leaf water potential of -13 bars. Experiments were conducted to determine whether the decrease in nitrate reductase activity was due to reduced levels of nitrate in the tissue, direct inactivation of the enzyme by low leaf water potentials, or to changes in rates of synthesis or decay of the enzyme.Although tissue nitrate content decreased with the onset of desiccation, it did not continue to decline with tissue desiccation and loss of enzyme activity. Nitrate reductase activity recovered when the plants were rewatered with nitrate-free medium, suggesting that the nitrate in the plant was adequate for high nitrate reductase activity. The rate of decay of nitrate reductase activity from desiccated tissue was essentially identical to that of the control, in vivo or in vitro, regardless of the rapidity of desiccation of the tissue. Direct inactivation of the enzyme by the low water potentials was not detected. Polyribosomal content of the tissue declined with the decrease in water potential, prior to the decline in nitrate reductase activity. Changes in ribosomal profiles occurred during desiccation, regardless of whether the tissue had been excised or not and whether desiccation was rapid or slow. Reduction in polyribosomal content did not appear to be associated with changes in ribonuclease activity. Nitrate reductase activity and the polyribosomal content of the tissue recovered upon rewatering, following the recovery in water potential. The increase in polyribosomal content preceded the increase in nitrate reductase activity. Recovery of enzyme activity was prevented by cycloheximide.Based on these results, it appears that nitrate reductase activity was affected primarily by a decrease in the rate of enzyme synthesis at low leaf water potentials.
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PMID:Nitrate Reductase Activity and Polyribosomal Content of Corn (Zea mays L.) Having Low Leaf Water Potentials. 1665 19

To elucidate the deleterious effects of excess lead on radish (Raphanus sativus) cv. Jaunpuri plants were grown in refined sand in complete nutrient solution for 30 days. On the 31st day lead nitrate was superimposed at 0.1 and 0.5mM to radish for 65 days. A set of plants in complete nutrient solution was maintained as control for the same period without lead. Excess Pb at 0.5mM showed growth depression with interveinal chlorosis on young leaves at apex. Excess Pb reduced the fresh and dry weight pronouncedly at d 65. Lead accumulation reduced the concentration of chlorophyll, iron, sulphur (in tops), Hill reaction activity and catalase activity whereas increased the concentration of phosphorus, sulphur (in roots) and activity of peroxidase, acid phosphatase and ribonuclease in leaves of radish.
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PMID:Excess lead alters growth, metabolism and translocation of certain nutrients in radish. 1792 49


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