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)

Acid-thermostable ribonucleases were isolated from human pancreas, duodenal contents, liver, spleen, serum and urine, and purified 15--1000-fold. The pH optima, ionic requirements, and some of the specificity requirements, of these enzymes were investigated. The isolated enzymes formed two distinct groups: (a) The ribonucleases of the pancreas, duodenal contents and fraction A of serum and urine exhibit a pH optimum of 8.5, are inhibited by An2+ and Cu2+, and relatively rapidly hydrolyze the synthetic substrate uridine 3'-(alpha-naphthylphosphate); (b) the ribonucleases of the liver and spleen, and of fractions B of the serum and urine, with a pH optimum of 7, are less sensitive to An2+ and Cu2+, and exhibit negligible activity versus uridine 3'-(alpha-naphthylphosphate). Determination of the serum level of pancreatic-type ribonuclease activity, with the use of uridine 3'-(alpha-naphthylphosphate) or RNA as substrates, appears to be a valid diagnostic tool for pancreatic fibrosis in children.
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PMID:Purification and properties of human acid-thermostable ribonucleases, and diagnosis of childhood pancreatic fibrosis. 0 43

Acid ribonuclease, free of nucleases and phosphatases, is isolated from rat thymus chromatin. The pH optimum of the enzyme is 5.0-5.5, optimal concentrations of Na+ and K+ ions are 0.05-0.15 M and 0.05 M respectively, Mg2+ inhibits the enzyme activity. The enzyme hydrolyses poly U, poly AU, cytoplasmic and nuclear RNAs, but does not attack poly A, polyG, polyC, poly A:poly U, native and denatured DNA'S. The enzyme is 3'-endonuclease, it splits the bond between the 5'-carbon atom of adenosine, guanosine and uridine and 3'-phosphate of uridilic residue. Middle length of oligonucleotides after the hydrolysis of cytoplasmic RNA comprises 10 nucleotides. Possible role of the enzyme in the processing of nuclear RNAs is discussed.
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PMID:[Characteristics of acid ribonuclease from rat thymus chromatin]. 1 99

Purified 15 S globin mRNA-protein (mRNP) complexes obtained by EDTA dissociation of duck reticulocytes polyribosomes were digested with the calcium dependant Staphylococcus aureus nuclease (EC 3. 1. 4. 7.). 25% of the globin mRNA sequences were resistant to extensive nuclease digestion as determined by TCA precipitation of the digested 15 S particles labelled in vivo with tritiated uridine. Polyacrylamide gel electrophoresis of the RNA from nuclease digested 15 S particles showed that the protected oligoribonucleotides were distributed into two distinct size classes of 25,000 and 12,000 MW. Comparison between in vitro iodine-labelled 9 S globin mRNA extracted from Staphylococcal nuclease digested 15 S mRNP particles was carried out by fingerprinting. Mapping of T1 ribonuclease digests by high-voltage electrophoresis and homochromatography showed that specific oligoribonucleotides were protected against nuclease attack by proteins of the 15 S mRNP.
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PMID:Evidence for the protection of specific RNA sequences in globin messenger ribonucleoprotein particles. 11 Dec 30

Incubation of Neurospora crassa conidia with ribonuclease (RNase) A reduces transport of L-phenylalanine by those cells. Under similar conditions, oxidized RNase A, RNase T1, and RNase T2 do not have this effect. Incubation of conidia with active RNase covalently attached to polyacrylamide beads reduces L-phenylalanine transport. This indicates that the site of enzymatic action is at the cell surface. At the lower concentration of enzyme used in this study, incubation with RNase A reduces transport of L-phenylalanine by the general (G) amino acid permease. Increasing the enzyme concentration results in reduction of transport by the neutral aromatic (N)-specific permease. The increased transport activity that accompanies onset of conidial germination is also sensitive to incubation with RNase A. Application of the enzyme to actively transporting cells does not release amino acid transported prior to enzyme addition. Cells cultured on media supplemented with [2-14C] uridine release isotopic activity after RNase A incubation. Analogous treatments with Pronase, RNase T1, RNase T2, or deoxyribonuclease I do not release isotope activity. Pronase treatment does reduce L-phenylalanine transport. Incubation of conidia with RNase A also inhibits germination of those conidia.
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PMID:Effects of ribonuclease A on amino acid transport in Neurospora crassa. 12 24

Purification and partial characterization of the poliovirus RNA-linked protein (VPg) are described. VPg has been freed from the RNA by ribonuclease digestion and phenol extraction. Gel filtration chromatography of VPg-pUp (labeled with 32P) in 0.5% sodium dodecyl sulfate or 6 M guanidine HCl indicates that it has a molecular weight of about 12,000. VPg is bound to the 5' end of poliovirion RNA by a phosphodiester bond between a tyrosine residue in the VPg molecule and the 5'-terminal uridine. After acid hydrolysis of [3H]tyrosine-labeled VPg-pU, free tyrosine can be released by venom phosphodiesterase. Acid hydrolysis of VPg-p labeled with either 32P or [3H] tyrosine yields tyrosine-phosphate. There appears to be only 1 tyrosine residue per VPg molecule.
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PMID:Protein is linked to the 5' end of poliovirus RNA by a phosphodiester linkage to tyrosine. 20 34

Treponema pallidum (Nichols) was extracted from infected rabbit tissue, and cell lysates were prepared for monitoring thymidine kinase and deoxyribonucleic acid polymerase activities. No thymidine kinase could be demonstrated in preparations of T. pallidum or the cultivable T. phagedenis biotype Reiter. Significant levels of deoxyribonucleic acid polymerase were detected in both treponemal samples. Interestingly, comparisons of polymerase activity among a spectrum of bacterial genera revealed a direct correlation between enzyme concentrations and estimated generation time. Incorporation of [3H]uridine and [3H]thymidine into macromolecules by intact T. pallidum and the Reiter treponeme was examined. Selective ribonuclease-deoxyribonuclease digestion and cesium chloride gradient banding demonstrated that T. pallidum, independent of the host, and T. phagedenis were capable of synthesizing deoxyribonucleic acid only from the [3H]-uridine precursor.
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PMID:Capacity of virulent Treponema pallidum (Nichols) for deoxyribonucleic acid synthesis. 37 16

The interaction of adenylyl-3',5'-cytidine (ApC) with ribonuclease-A (RNAase-A) was studied by steady-state kinetics and ultraviolet difference spectroscopy. X-ray difference Fourier synthesis at 4 A resolution was also used to study the binding of ApC to RNAase-S. Unlike well-studied compounds like uridylyl-3',5'-adenosine, ApC binds in an unique way: (1) the cytidine moiety is bound to the B1 and R1 sites, (2) the adenosine moiety protrudes to the solution and is not fixed spatially and (3) the phosphate group is bound to the non-specific site (the "Po site") previously postulated (Sawada, F. and Irie, M. (1969) J. Biochem. (Tokyo) 66, 415--418) as the binding site for the 5'-phosphate of uridine 2',5'-diphosphate or uridine 3',5'-diphosphate. This conclusion is consistent with that derived for adenylyl-3',5' -4-thiouridine based on CD difference spectroscopy (White, M.D., Keren-Zur, M. and Lapidot, Y. (1977) Nucleic Acid Res. 4, 843--851). The "Po site" is most likely the epsilon-amino group of Lys 66.
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PMID:Studies on the binding of adenylyl-3', 5'-cytidine to ribonuclease. 67 53

The kinetics of 3H-uridine incorporation into measles-infected Vero cells demonstrated that maximum virus-specific RNA synthesis occurred between 16 and 20 h after infection. Sedimentation analysis on sucrose gradients revealed the presence of four species of RNA having sedimentation coefficients 4S, 12 to 26S, 28 to 36S and 50S. Annealing studies showed that RNA sedimenting in the 12 to 36S regions was 100% complementary in base sequence to nucleocapsid 50S RNA, and at least 96% of the 50S genomic RNA was transcribed during virus replication. Polynucleotide binding experiments ane ribonuclease treatment indicated that poly(A) sequences were associated with the intracellular 12 to 26S, 28 to 36S and 50S RNAs. Denaturation of intracellular 50S RNA followed by sucrose gadient centrifugation demonstrated that this was a mixture of genomic 50S and heterogeneous RNAs which sedimented at 4 to 40S. The genomic RNA did not contain poly(A) sequences, and these are presumably associated with the heterogeneously sedimenting RNAs. The size of poly(A) sequences present on the 12 to 36S RNAs was estimated to be in the range of 70 to 140 nucleotides. Treatment of the 12 to 36S RNAs and their poly(A) sequences with polynucleotide phosphorylase indicated that the poly(A) was located on the 3' end of the RNAs, but that under the experimental conditions used this was protected by the secondary structure of the molecules.
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PMID:Rolyadenylic acid [poly(A)] sequences associated with measles virus intracellular ribonucleic acid (RNA) species. 88 16

Purification of feline calicivirus was achieved by cycles of differential centrifugation and two cycles of sucrose gradient centrifugation. Feline calicivirus grown in the presence of Actinomycin D and 3H-uridine-5, sediments in 15% to 45% sucrose gradients and forms a peak of radioactivity which corresponds with the peak of infectivity. Ribonucleic acid (RNA) extracted from the peak radioactive fractions taken from the sucrose gradient sedimented as a single peak ahead of the 28S peak of cellular RNA. It was sensitive to ribonuclease and was presumed to be single stranded feline calicivirus RNA with sedimentation of 32S-35S. A single peak of radioactivity at 35S was extracted from purified virus by heating at 60 degrees for two minutes in 1% sodium dodecyl sulphate (SDS), or by heating at 37 degrees for 5 minutes at 1% SDS. Virus extracted at 37 degrees for 10 minutes in 1% SDS showed also a small peak at 16S and by 15 minutes at 37 degrees only a broad peak at 16S occurred. All peaks were susceptible to ribonuclease. A component sedimenting at 18S which was resistent to degradation by ribonuclease under the conditions outlined by Baltimore (4) and presumed to be double-stranded RNA was present in kitten kidney cells infected with feline calicivirus.
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PMID:Feline calicivirus: purification of virus and extraction and characterisation of its ribonucleic acid. 97 39

The stability of Escherichia coli polysomes at increased hydrostatic pressure was investigated in actively growing cells, in which the initiation of transcription was blocked by rifampin. In these cells, [3-H]uridine incorporation into messenger ribonucleic acid and the subsequent degradation of the message (and therefore of polysomes) by ribonuclease could be observed. Evidence is presented that the activity of the RNases is unaffected by a pressure of 680 atm, that protein synthesis is completely inhibited at 680 atm but immediately resumes at the 1 atm rate on release of pressure, and that no degradation of messenger ribonucleic acid in polysomes occurs at 680 atm. The effects of pressure; puromycin, and chloramphenicol on polysomal degradation are discussed. These results indicate that, contrary to some previous reports, polysomes are probably stabilized by high pressures. Therefore, we consider that polysomal instability is not a factor in the inhibition of protein synthesis by high pressures.
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PMID:Stability of Escherichia coli polysomes at high hydrostatic pressure. 109 Jun 1


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