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:3.1.26.9 (ribonuclease)
6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A ribonuclease associated with vaccinia virus can be detected when reduced concentrations of nucleotides are used for an in vitro RNA synthesis assay. The non-viral origin of this ribonuclease may be inferred from its external location and from its variable activity on different purified virus stocks. The detection of this ribonuclease activity on purified virus grown without foetal Calf serum may suggest that this enzyme is of cellular origin.
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PMID:[Detection and localization of a ribonuclease activity associated with vaccinia virus]. 12 Jul 81

Extracts of vaccinia-infected HeLa cells were rendered free from infectious virus by centrifugation followed by membrane filtration and were shown to be toxic to uninfected HeLa cells in the presence of hypertonic MgSO4, used as a macromolecular uptake inducer, under conditions which did not kill control cells. Extracts from uninfected cells were nontoxic. This biological test was adapted to a semi-quantitative assay which was used to monitor the purification of the cytotoxic factor by DEAE-cellulose and Sephadex G-100 chromatography. The cytotoxic factor was purified 100-fold, shown to be of molecular weight 30 -- 100,000 daltons, acidic and completely inactivated by soluble trypsin but not by ribonuclease under conditions believed to degrade both single- and double-stranded RNA species. It was demonstrated to be virus specific by approrpiate immunosorbent chromatography. Extracts were also prepared from vaccinia-infected HEp-2, RK and W-K cells respectively. A virus-specific factor, toxic to uninfected HeLa cells, with similar chromatographic properties to that isolated from infected HeLa cells, was isolated from these three additional cell lines. The concept of virus induced cytotoxins, substances which exert their toxic effect in the host cells in which they are made, is discussed.
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PMID:Vaccinia virus cytotoxin. 85 98

The synthesis of vaccinia virus double-stranded ribonucleic acid (RNA) in infected HeLa cells was sensitive to actinomycin D, suggesting that a deoxyribonucleic acid dependent reaction is involved. Some double-stranded RNA was made in the presence of cytosine arabinoside in infected cells. Double-stranded and complementary RNA were synthesized in vitro by using vaccinia cores. These two observations indicate that some of the double-stranded RNA is read from "early" genes. The double-stranded RNA synthesized in vitro had the same properties as that made in vivo. At least 70% of the double-stranded RNA made in vivo was in ribonuclease-resistant form prior to sodium dodecyl sulfate-phenol extraction. In addition, there was a complementary RNA in infected cells which could be converted to double-stranded RNA by annealing.
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PMID:Mechanism of synthesis of vaccinia virus double-stranded ribonucleic acid in vivo and in vitro. 554 34

Labelled vaccinia virus DNA was used in saturation-hybridization experiments with RNA extracted from virus-infected cells. An excess of "late" cytoplasmic RNA converted 45% of DNA into DNA-RNA hybrids, whereas 17% of DNA could be converted into hybrids by RNA extracted from purified nuclei. RNA-RNA hybrids obtained from cytoplasmic RNA by self-annealing and ribonuclease treatment, were melted and used in hybridization with DNA: 36% of DNA was hybridized at the maximal concentration used.
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PMID:RNA sequences of opposite polarities transcribed from a large part of vaccinia virus genome are accumulated in the cytoplasm. 611 Dec 6

Highly purified yeast RNA polymerase III ternary complexes were found to possess a hydrolytic chain retracting activity that cleaves nascent RNA from its 3'-OH end. Most of the shortened transcripts were capable of resuming RNA chain elongation, indicating that they remain stably associated with the enzyme-DNA complex. Analysis of the products of cleavage indicated that retraction primarily occurred in dinucleotide increments, but that mononucleotides were also excised at lower frequency. The ribonuclease activity was totally dependent on the presence of a divalent cation and was stimulated by the addition of non-cognate ribonucleotides. The inclusion of ATP in the reaction enhanced both the rate and extent of transcript cleavage. Evidence suggesting that the hydrolytic activity is intrinsic to RNA polymerase III and factor-independent is also presented. Transcript cleavage by RNA polymerase III ternary complexes appears to be more closely related to the intrinsic nucleolytic activity of vaccinia virus RNA polymerase ternary complexes than to TFIIS-dependent cleavage that has been described for RNA polymerase II ternary complexes.
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PMID:Hydrolytic cleavage of nascent RNA in RNA polymerase III ternary transcription complexes. 750 90

To define protein domains important for activation of the interferon (IFN)-induced enzyme 2-5A-dependent RNaseL, we have generated vaccinia virus (VV) recombinants able to express in cultured cells truncated forms of this protein and compared their biologic activities with those producing the wild-type enzyme, with and without coexpression of 2-5A synthetase. Our results show that full activation of RNaseL requires binding of 2-5A oligonucleotides within amino acid positions 212-339, corresponding to ankyrin repeats 6 to 9. The protein kinase and ribonuclease domains of RNaseL, amino acids 340-741, are sufficient for a constitutively active enzyme that is unresponsive to excess 2-5A. These results demonstrate in vivo the importance of the ankyrin domains in the biologic function of RNaseL. We suggest that ankyrin repeats act as key modulators of RNaseL activity.
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PMID:Full activation of RNaseL in animal cells requires binding of 2-5A within ankyrin repeats 6 to 9 of this interferon-inducible enzyme. 1009 Mar 96

The review is devoted to angiogenin, one of the factors that induce formation of blood vessels, which is unique among them in that it is a ribonuclease. Consideration is given to the tertiary structure of human angiogenin; the catalytic and cell-receptor binding sites, their significance for angiogenic activity; the human angiogenin gene structure, chromosomal localization, and expression; the specificity of angiogenin as a ribonuclease and abolishment of protein synthesis; the nuclear localization of angiogenin in proliferating endothelial cells and its significance for angiogenic activity; angiogenin binding to a cell-surface actin as a plausible mechanism of inducing neovascularization (enhancement of plasminogen activation by actin with angiogenin, stimulation of the cell-associated proteolytic activity by angiogenin; promotion of the cultured cells invasiveness); modulation of mitogenic stimuli in endothelial, smooth muscle, and fibroblast cells by angiogenin. The importance of angiogenin as an adhesive molecule for endothelial and tumor cells is discussed too, as well as the modulation of tubular morphogenesis by bovine angiogenin, prevention of tumor growth in vivo by angiogenin antagonists, prospects of the use of angiogenin and angiogenin-encoding recombinant plasmids and vaccinia virus in therapeutic practice.
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PMID:[Angiogenin and its role in angiogenesis]. 1144 14

Vaccinia type I DNA topoisomerase exhibits a strong site-specific ribonuclease activity when provided a DNA substrate that contains a single uridine ribonucleotide within a duplex DNA containing the sequence 5' CCCTU 3'. The reaction involves two steps: attack of the active site tyrosine nucleophile of topo I at the 3' phosphodiester of the uridine nucleotide to generate a covalent enzyme-DNA adduct, followed by nucleophilic attack of the uridine 2'-hydroxyl to release the covalently tethered enzyme. Here we report the first continuous spectroscopic assay for topoisomerase that allows monitoring of the ribonuclease reaction under multiple-turnover conditions. The assay is especially robust for high-throughput screening applications because sensitive molecular beacon technology is utilized, and the topoisomerase is released during the reaction to allow turnover of multiple substrate molecules by a single molecule of enzyme. Direct computer simulation of the fluorescence time courses was used to obtain the rate constants for substrate binding and release, covalent complex formation, and formation of the 2',3'-cyclic phosphodiester product of the ribonuclease reaction. The assay allowed rapid screening of a 500 member chemical library from which several new inhibitors of topo I were identified with IC(50) values in the range of 2-100 microM. Three of the most potent hits from the high-throughput screening were also found to inhibit plasmid supercoil relaxation by the enzyme, establishing the utility of the assay in identifying inhibitors of the biologically relevant DNA relaxation reaction. One of the most potent inhibitors of the vaccinia enzyme, 3-benzo[1,3]dioxol-5-yl-2-oxoproprionic acid, did not inhibit the closely related human enzyme. The inhibitory mechanism of this compound is unique and involves a step required for recycling the enzyme for steady-state turnover.
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PMID:Ribonuclease activity of vaccinia DNA topoisomerase IB: kinetic and high-throughput inhibition studies using a robust continuous fluorescence assay. 1555 7

It has been possible by means of classical chemical methods to isolate and to characterize to some extent the nucleic acid of elementary bodies of vaccinia. Determination by means of diphenylamine reagent revealed that the major part of the nucleic acid was of the thymus type. This was further substantiated by its stability in the presence of ribonuclease, less than 10 per cent undergoing depolymerization during prolonged incubation at 37 degrees C. By the technique employed, at least 5.6 per cent of the virus was shown to be thymonucleic acid. This amount agreed favorably with the value calculated from the non-lipid organic phosphorus of elementary bodies on the assumption that the phosphorus bound in the organic form was derived principally from nucleic acid.
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PMID:CONSTITUENTS OF ELEMENTARY BODIES OF VACCINIA : II. PROPERTIES OF NUCLEIC ACID OBTAINED FROM VACCINE VIRUS. 1987 Oct 13

The effects of a number of crystalline and highly purified enzymes on elementary bodies of vaccinia are reported. These effects have been followed by determination of amino nitrogen, staining reaction, and studies of infectivity. Pepsin, at a pH which inactivates the virus, results in its solution and rapid release of amino nitrogen. Crystalline trypsin, chymotrypsin, carboxypeptidase, and ribonuclease are without appreciable effect on the virus. Papain within a short time produces profound alteration in the staining reaction of the elementary body with release of amino nitrogen accompanied by complete inactivation of the virus. This reaction is not shared by crystalline ficin, another plant papain, or by cathepsin, an intracellular proteinase analogous to plant papains but of animal origin.
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PMID:CONSTITUENTS OF ELEMENTARY BODIES OF VACCINIA : III. THE EFFECT OF PURIFIED ENZYMES ON ELEMENTARY BODIES OF VACCINIA. 1987 Oct 53


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