Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A pancreatic ribonuclease digest of (14)C-labeled tobacco necrosis virus RNA was fractionated according to charge by column chromatography. Individual fractions were dephosphorylated with alkaline phosphatase and rechromatographed. The fraction, originally containing oligonucleotides with seven negative charges, separated into two components corresponding to five (-5) and two negative charges (-2). The -5 fraction was derived from the internal oligonucleotides while the -2 fraction must have originated from a 5'-pyrophosphorylated terminal trinucleotide. The sequence of this terminal trinucleotide was determined by column chromatography on DEAE-cellulose in a triethyl ammonium carbonate gradient, using the appropriate markers. The radioactivity chromatographed with a (ApGp)U marker. The order of the Ap and Gp was determined after ribonuclease T(1) and alkaline phosphatase digestion. The radioactivity in the product chromatographed with an ApG marker. The 5'-terminus of tobacco necrosis virus RNA was therefore determined as ppApGpUp..., which is identical to the terminus of the RNA of its satellite virus as previously determined (J. Mol. Biol., 38, 59 (1968); Science, 160, 1452 (1968)). The 5' pyrophosphate in both viruses was probably formed by an in vivo enzymatic removal of a gamma-phosphate from a triphosphate, and its presence in both viruses suggested a common site of synthesis. The identity of the 5'-terminal sequences is considered not to be fortuitous and is discussed from the standpoint of their role as a recognition site for the virus-specific RNA replicase.
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PMID:Identity of the 5'-terminal RNA nucleotide sequence of the satellite tobacco necrosis virus and its helper virus: possible role of the 5'-terminus in the recognition by virus-specific RNA replicase. 527 92

Presence of carbonate anions increases the oxidation of luminol in different chemical systems. Lysis of human erythrocytes due to the action of dihydroxyfumaric acid or of perborate is also stimulated by carbonate ions. These anions also change considerably the loss of activity of different enzymes treated with superoxide, hydroxyl or formate radicals and can increase or decrease the effect as a function of the nature of the active centre of the enzyme. The relative effects of superoxide, hydroxyl, formate and carbonate radicals for the inactivation of various enzymes (superoxide dismutases, catalase, ribonuclease, glucose oxidase and glutathione peroxidase) have been examined. Three systems were used: gamma-irradiation under different conditions, photoproduction of radicals and sonication. Inactivation of the enzymes is a function not only of the radical used but also of the nature of the active site. Thus glutathione peroxidase is remarkably resistant to hydroxyl radicals while the superoxide dismutases are rapidly inactivated by carbonate radicals. All of the results combine to show that the presence or absence of carbonate anions must be considered in all studies of oxygen containing free radicals whether chemical, biochemical or biological or high energy irradiation.
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PMID:Carbonate anions; effects on the oxidation of luminol, oxidative hemolysis, gamma-irradiation and the reaction of activated oxygen species with enzymes containing various active centres. 630 56

Although the AE1 chloride/bicarbonate exchanger of the red blood cell is among the most thoroughly investigated of membrane transport proteins, less is known about the related AE2 polypeptide of parietal cells. We have studied enzymatic deglycosylation of native AE2 polypeptide in gastric mucosal membranes from pig and rabbit. Deglycosylation of AE2 was maximal at low ionic strength. Deglycosylation of AE2 in membranes was preferentially inhibited by bicarbonate compared with other anions. This inhibition was maximal at alkaline pH and was not evident after detergent solubilization of AE2. Deglycosylation of AE2 increased its susceptibility to proteolytic degradation, but the presence of bicarbonate protected against this degradation. Bicarbonate failed to inhibit deglycosylation of the membrane glycoproteins AE1 and gastric H(+)-K(+)-adenosinetriphosphatase beta-subunit or deglycosylation of the soluble glycoproteins fetuin and ribonuclease B. These data suggest that bicarbonate induces a conformational change in AE2 that can protect the polypeptide from deglycosylation and proteolysis. Pig AE2 was purified in sodium dodecyl sulfate, and its monosaccharide composition was determined after blotting onto polyvinylidene fluoride membrane. AE2 was found to be devoid of sialic acid, with a composition suggestive of the presence of lactosamine-type chains.
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PMID:HCO3(-)-dependent conformational change in gastric parietal cell AE2, a glycoprotein naturally lacking sialic acid. 877 47

The reactions of a ribonuclease model substrate, the compound uridine-3'-p-nitrophenyl phosphate, have been examined using heavy-atom isotope effects and stereochemical analysis. The cyclization of this compound is subject to catalysis by general base (by imidazole buffer), specific base (by carbonate buffer), and by acid. All three reactions proceed by the same mechanistic sequence, via cyclization to cUMP, which is stable under basic conditions but which is rapidly hydrolyzed to a mixture of 2'- and 3'-UMP under acid conditions. The isotope effects indicate that the specific base-catalyzed reaction exhibits an earlier transition state with respect to bond cleavage to the leaving group compared to the general base-catalyzed reaction. Stereochemical analysis indicates that both of the base-catalyzed reactions proceed with the same stereochemical outcome. It is concluded that the difference in the nucleophile in the two base-catalyzed reactions results in a difference in the transition state structure but both reactions are most likely concerted, with no phosphorane intermediate. The (15)N isotope effects were also measured for the reaction of the substrate with ribonuclease A. The results indicate that considerably less negative charge develops on the leaving group in the transition state than for the general base-catalyzed reaction in solution. Copyright 2000 Academic Press.
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PMID:Kinetic Isotope Effects and Stereochemical Studies on a Ribonuclease Model: Hydrolysis Reactions of Uridine 3'-Nitrophenyl Phosphate. 1091 50

Secondary hyperparathyroidism is characterized by increased parathyroid hormone (PTH) mRNA stability that leads to increased PTH mRNA and serum PTH levels. PTH gene expression is reduced by the calcimimetic R568 and the oral phosphorus binder lanthanum carbonate (La). Changes in PTH mRNA stability are regulated by the binding of trans-acting stabilizing and destabilizing factors to a defined cis element in the PTH mRNA 3'-untranslated region (UTR). Adenosine-uridine (AU)-binding factor 1 (AUF1) is a PTH mRNA-stabilizing protein, and K-homology splicing regulatory protein (KSRP) is a destabilizing protein that targets mRNAs, including PTH mRNA, to degradation by the ribonuclease complex exosome. We now show that KSRP-PTH mRNA binding is decreased in parathyroids from rats with adenine-induced chronic kidney disease (CKD) where PTH mRNA is more stable. KSRP-PTH mRNA binding is increased by treatment with both R568 and La, correlating with decreased PTH gene expression. In vitro degradation assays using transcripts for PTH mRNA and rat parathyroid extracts reproduce the differences in mRNA stability in vivo. Accordingly, PTH mRNA is destabilized in vitro by parathyroid extracts from CKD rats treated with R568 or La compared with parathyroid extracts from untreated CKD rats. This destabilizing effect of R568 and La is dependent on KSRP and the PTH mRNA 3'-UTR. Therefore, the calcimimetic R568 and correction of serum phosphorus by La determine PTH mRNA stability through KSRP-mediated recruitment of a degradation complex to the PTH mRNA, thereby decreasing PTH expression.
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PMID:Regulation of PTH mRNA stability by the calcimimetic R568 and the phosphorus binder lanthanum carbonate in CKD. 1912 57

Magnesium-stabilized amorphous calcium carbonate (Mg-ACC), amorphous magnesium calcium silicate hydrate (MCSH), and hydroxyapatite (HAp) are prepared by a precipitation method. By cold-pressing these particles, it is possible to produce porous bulk discs with a narrow pore size distribution. These porous inorganic discs (Mg-ACC, MCSH, and HAp) are investigated as stationary phases to study the chromatographic behavior and adsorption ability of rhodamine B, methylene blue, and ribonuclease. The adsorption affinities of different biomolecules can be easily observed and evaluated through this method. Furthermore, by infiltrating fabricated opaque porous discs with benzyl ether, which has a similar refractive index as the used inorganic particles (Mg-ACC, MCSH, and HAp), their optical properties significantly change and the discs become translucent. Moreover, by infiltrating the MCSH discs with a light-curing polymer, translucent composites with good surface hardness are fabricated. By doping particles with ions such as Ni2+, Co2+, Fe3+, and Eu3+, the color and UV-visible spectrum of the bulk discs can be adjusted. Typically, by using iron-doped MCSH particles as the inorganic matrix, nanocomposites, which show a steep UV-absorption edge at 400 nm, are fabricated. Our work provides a simple and economical method to evaluate the affinity of biomolecules to inorganic materials and a novel way to fabricate translucent hard composite materials. The fabricated nanocomposite discs show a great UV shielding effect and superior surface hardness compared to polymethyl methacrylate and commercial sunglasses, suggesting their potential as new sunglass materials.
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PMID:Inorganic Porous Bulk Discs as a Matrix for Thin-Layer Chromatography and Translucent Hard Composite Materials. 3182 82

Bicarbonate (NaHCO3) stress was usually considered to be a mixed stress with salts and high pH. The NaHCO3-specific signaling in plants were rarely reported. In this study, transcriptome analyses was conducted in order to identify the NaHCO3-specific singling in Arabidopsis. Weighted correlation network analysis were performed to isolate the NaHCO3-specific modules in comparison to acetate treatment. The genes in the NaHCO3-root-specific module, which exhibited opposite expressions between NaHCO3 and sodium acetate treatments, were further examined with their corresponding knock-out mutants. The gene Exclusively Bicarbonate Sensitive 1 (EBS1) encoding an S-ribonuclease binding protein was identified to be specifically involved in plant tolerance to NaHCO3, but not to the other two alkaline salts, acetate and phosphate. We also identified the genes that commonly regulated by bicarbonate, acetate and phosphate. Multiple brassinosteroid associated gene ontology terms were enriched in these genes. Via genetic assays, it was found that brassinosteroid signaling positively regulated plant tolerance to NaHCO3 stress while negatively regulated tolerance to acetate and phosphate. Overall, our data genetically identified the bicarbonate-specific genes, and conclude that alkaline stress is mainly dependent on the specificities of the weak acid ions rather than high pH.
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PMID:An S-ribonuclease binding protein EBS1 and brassinolide signaling are specifically required for Arabidopsis tolerance to bicarbonate. 3316 37