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

The DNAase in human urine was purified about 30-fold with a recovery of 28%. This involved DEAE-cellulose and phosphocellulose chromatography steps and gel filtration on Sephadex G-75. The enzyme required divalent cations such as Co2+, Mg2+, Mn2+ and Zn2+ for activity, but Ca2+, Cu2+ and Fe2+ were ineffective. EDTA and G-actin inhibited the reaction. The maximum activity was observed at pH 5.5 in acetate buffer plus Co2+ or Mg2+ and Ca2+. It had a molecular weight of approximately 38 000, estimated by gel filtration on Sephadex G-75 and isoelectric point of around pH 3.9. The enzyme is an endonuclease which hydrolyzes native, double-stranded DNA about 3 to 4 times faster than thermally denatured DNA to produce 5'-phosphoryl- and 3'-hydroxyl-terminated oligonucleotides. The final preparation was free of non-specific acid and alkaline phosphatases, phosphodiesterase and ribonuclease activities.
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PMID:Purification and properties of deoxyribonuclease from human urine. 2 31

By sequential acid treatment, gel filtration and KM-cellulose sorption a 18--20-fold purified preparation of ribonuclease with a yield of 50--60% was obtained from the culture liquid filtrate of Actinomyces rimosus 994. The preparation had a high specific activity of 450,000--600,000 units/mg protein, contained 85--98% protein, insignificant amounts of carbohydrates and hydroxytetracycline, and no quantities of DNase, phosphomonoesterases, phosphodiesterase or proteases. In RNA degradation (preparation of the total yeast RNA of the Sigma Co.) optimal results were obtained at 50 degrees C and pH 7.0--7.2 in phosphate buffer and 7.6--8.0 IN Tris-HCl buffer. The preparation was stable at high temperatures (80--100 degrees) in the wide pH range and during storage in the lyophilized form and in buffer solutions. RNase effect was inhibited by zinc, copper, iron and cobalt cations and activated by beta-mercaptoethanol, citrate and EDTA. Protamine sulphate and urea in low concentrations (0.01% and 1--4 M, respectively) accelerated and in high concentrations (1% and 8 M, respectively) terminated the enzyme reaction. With respect to many properties RNase from Act. rimosus 994 was similar to extracellular RNases, produced by other actinomycetes and fungi.
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PMID:[Preparation of extracellular ribonuclease form Actinomyces rimosus 994]. 3 16

An endo-type, cyclising, 3'-phosphate-forming rebonuclease was purified to homogeneity from a water/Tween 80 extract of human hypertrophic prostate gland. The enzyme is acid- and heat- resistant and is optimally active at pH 7.0, 0.1 M NaCl. Molecular weight determined by gel filtration on Sephadex G-75 and sucrose density gradient centrifugation gave a mean value of 15 000. The prostatic ribonuclease is inhibited by Cu2+, bromoacetate and photooxidation in the presence of methylene blue. Other divalent ions, EDTA and p-chloromercuribenzoate have no influence on the enzymic activity. Prostatic RNase resembles RNase A in that it preferentially cleaves linkages in RNA after pyrimidine nucleotides to produce oligonucleotides terminated in cyclic 2',3' phosphate. The enzyme is inactive with poly(A) - poly(U) as substrate. Poly(U) is hydrolyzed four times as fast as poly(C), and 1.2 times as fast as RNA.
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PMID:Preparation and characterisation of ribonuclease from human hypertrophic prostate gland (RNAase P2). 5 49

1. A ribonuclease (RNAase CL) (EC 3.1.4.23, ribonucleate 3'-oligonucleotide hydrolase) was extracted by EDTA/acetate buffer, pH 5.6 from acetonedried cells of Candida lipolytica and purified 1350-fold by acetone and (NH4)2SO4 fractionation, DEAE-cellulose and DEAE-Sephadex chromatography. 2. RNAase CL is an acidic protein having an isoelectric point of 4.2, and an approximate molecular weight of 32 000. 3. Optimal pH and temperature for the enzyme were 6.0 and 60 degrees C, respectively. It is stable at neutral pH up to 50 degrees C. At 64 degrees C for 30 min, 95, 49 and 64% inactivation of the enzyme occurred at pH values 4.2, 6.6 and 10.0, respectively. 4. RNAase CL inhibited by Zn2+ and Cu2+, sulfhydryl reactants and by high concentration of salts, but not by chelating agents. 5. RNAase CL degraded ribosomal RNA, transfer RNA, polyadenylic acid, polycytidylic acid and polyuridylic acid into acid-soluble nucleotides. Among the synthetic homopolymers, polycytidylic acid was most rapidly degraded. Polyguanylic acid and duplexes of synthetic homopolymers were less sensitive. DNA was not attacked. Specificity studies showed that RNAase CL preferentially cleaves pC-purine bonds. 6. Digestion of poly (C) by RNAase CL resulted in the liberation of cyclic 2',3'-CPM from the start of the reaction with no observable formation of intermediate oligonucleotides. This suggests that the enzyme depolymerizes by an exonucleolytic mechanism.
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PMID:Puridication and properties of an intracellular ribonuclease from Candida lipolytica. 23 21

Chromatography of commercial rennet was studied on biospecific sorbents obtained by means of coupling of activated Sepharose 4B with epsilon-aminocapronyl-D-phenylalanine methyl ester and amide, epsilon-aminocapronyl-L-phenylalanyl-D-phenylalanine methyl ester, gramicidin S and N-2,4-dinitrophenylhexamethylenediamine. A mixture of two similar on their specificity enzymes chymosin and bovine pepsin was isolated from rennet by the chromatography on these sorbents. The individual enzymes might be isolated by chromatography on immobilized ribonuclease at pH 3,0, or by means of electrofocusing in pH gradient 4-6. Coloured inhibitor of acid proteases, N-diazoacetyl-N'-2,4-dinitrophenyl-ethylenediamine (DDE) is found to inactivate chymosin at pH 5,6 in the presence of Cu2+,one residue of the inhibitor being attached to the enzyme molecule. Unlike pig pepsin, chymosin is not inhibited with DDE at pH 4,7 and at the enzyme:DDE:Cu2+ ratio being 1:40:40. a synthesis of peptide sorbents is described.
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PMID:[Biospecific chromatography of chymosin]. 77 34

With the glutathione system that leads to rapid regeneration of reduced lysozyme (Saxena, V. P., and Wetlaufer, D. B. (1971) Biochemistry 9, 5015), reduced pancreatic ribonuclease (RNase) regenerated activity in high yield (greater than 90%) but at a considerably lower rate (t1/2 approximately 75 min). Systematic examination of the effects upon regeneration of the concentrations and ratios of reduced and oxidized glutathione (GSH and GSSG) showed the same broad optima for RNase as were earlier found for lysozyme: [GSSG] = 5 X 10(-4) M, [GSH] = 5 X 10(-3) M. Regeneration of reduced RNase by air oxidation was shown to be inhibitable by 10(-4) M EDTA, whereas the glutathione regeneration was unaffected by EDTA. In addition the air-oxidative regeneration showed a strong temperature dependence, in contrast with the glutathione system. The mechanisms of these two kinds of regenerations are therefore different. Six potentially catalytic metal ions were tested in the air-oxidative regeneration of RNase: Cu2+, Co2+, Mn2+, Fe3+, Zn2+, and Ni2+. Of these, only Cu2+ enhanced the rate of regeneration of RNase activity, although both Cu2+ and Co2+ catalyzed thioloxidation of reduced RNase. The rates and yields of RNase regenerations were independent of protein concentration from 3 X 10(-7) M to 1.2 X 10(-5) M in the glutathione system. Preincubation of freshly dissolved reduced RNase under nonoxidizing conditions before adding glutathione did not change the rate or extent of regeneration. Studies of its pH dependence showed that the glutathione regeneration depends on the deprotonation of prototropic groups with 7.5 less than pK less than 8.0. The major ion exchange chromatographic peaks from glutathione and air-oxidative regenerations appeared to be identical with native RNase, by the criteria of specific activity, chromatographic mobility, and circular dichroic spectra. The glutathione system permits regeneration at much higher RNase concentration than the air regeneration, with rates and yields comparable to the greatest reported for air regeneration.
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PMID:Nonenzymic reactivation of reduced bovine pancreatic ribonuclease by air oxidation and by glutathione oxidoreduction buffers. 119 63

Angiogenin is a potent blood-vessel-inducing polypeptide with a molecular weight of 14,000 that has a unique ribonucleolytic activity. First isolated from the conditioned medium of tumour cells, angiogenin has since been purified from normal plasma, which suggested that its propensity to induce neovascularization should be strictly controlled. Modulation of that activity might involve interaction of angiogenin with cell-surface receptors and extracellular matrix of endothelial cells, tight-binding inhibition of both its ribonucleolytic activity and cell binding property by ribonuclease inhibitor, as well as the overall influence of divalent copper, a modulator of angiogenesis.
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PMID:In vivo and in vitro studies of angiogenin--a potent angiogenic factor. 172 10

We have used equilibrium binding analyses to evaluate the influence of temperature and urea on the affinity of hen egg white lysozyme and bovine pancreatic ribonuclease A for surface-immobilized Cu(II) ions. Linear Scatchard plots suggested that these model proteins were interacting with immobilized metal ions via a single class of intermediate-affinity (Kd = 10-40 microM) binding sites. Alterations in temperature had little or no effect on the immobilized Cu(II) binding capacity of either protein. Temperature effects on the interaction affinity, however, were protein-dependent and varied considerably. The affinity of lysozyme for immobilized Cu(II) ions was significantly decreased with increased temperature (0 degree C-37 degrees C), yet the affinity of ribonuclease did not vary measurably over the same temperature range. The van 't Hoff plot (1n K vs 1/T) for lysozyme suggests a straight line relationship (single mechanism) with a delta H of approximately -5.5 kcal/mol. Urea effects also varied in a protein-dependent manner. A 10-fold reduction in the affinity of lysozyme for the immobilized Cu(II) was observed with the urea concentrations up to 3 M; yet urea had no effect on the affinity of ribonuclease for the immobilized metal ions. Although the interaction capacity of lysozyme with the immobilized Cu(II) ions was decreased by 50% in 3 M urea, ribonuclease interaction capacity was not diminished in urea. Thus, temperature- and urea-dependent alterations in protein-metal ion interactions were observed for lysozyme but not ribonuclease A. The complete, yet reversible, inhibition of lysozyme- and ribonuclease-metal ion interactions by carboxyethylation with low concentrations of diethylpyrocarbonate provided direct evidence of histidyl involvement. The differential response of these proteins to the effects of temperature and urea was, therefore, interpreted based on calculated solvent-accessibilities and surface distributions of His residues, individual His residue pKa values, and specific features of the protein surface structure in the immediate environment of the surface-exposed histidyl residues. Possible interaction mechanisms involved in protein recognition of macromolecular surface-immobilized metal ions are presented.
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PMID:Protein interactions with surface-immobilized metal ions: structure-dependent variations in affinity and binding capacity with temperature and urea concentration. 185 19

Metallothioneins that bind copper and zinc have an Mr of 6500 daltons, consist of a single polypeptide chain of 61 amino acids, 25-30 percent of whose residues are cysteine, have a metal-binding capacity of between 5 and 7 g atoms/mol, and contain no disulfide bonds or aromatic amino acids. Zincthionein has been postulated to participate in the transport and storage of zinc, which is involved in more than 235 metalloenzymes, including thymidine kinase, RNA polymerase, and ribonuclease, which in turn play crucial roles in the replication and transcription of DNA during cell division. In addition, trace elements including zinc modulate immune response and function. Conversely, zinc deficiency state causes, for example, thymic atrophy and lymphopenia and modifies antibody-mediated responses to both T-cell-dependent and T-cell-independent antigens. The concentrations of copper, zinc, and metallothionein and the copper/zinc ratio are modified in a number of malignancies. For example, the levels of metallothionein in normal and in malignant human livers are 471 and 75 micrograms/g, respectively. In addition, the copper/zinc ratio is significantly increased in human pancreatic cancer from 1.40 to 2.70. Furthermore, studies involving 64Cu in tumor-bearing mice showed that the distribution of 64Cu was altered and that all tumors contained a relatively high level of 64Cu. Moreover, the activity of superoxide dismutase to remove free oxygen radicals is lower in malignant tissues. Finally, the results of clinical studies suggest that the monitoring of the serum copper/zinc ratio may be a valuable tool, not only in determining the extent of malignancies, but also in predicting the efficacy of treatments.
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PMID:The status of zinc, copper, and metallothionein in cancer patients. 328 43


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