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)

1. Fragments of isolated rat liver plasma membrane possess a ribonuclease activity which at pH 7.8 in the presence of 10 mM EDTA can digest polyuridylic acid (poly(U)) and polycytidylic acid (poly(C)) but not polyadenylic acid (poly(A)) and polyguanylic acid (poly(G)). Under these conditions, the membrane preparation does not degrade native or denatured DNA. 2. The products of the reaction with poly(U) (10 mM EDTA present) can be separated on DEAE-Sephadex into oligonucleotides of increasing chain length. Most of the products are di- to hexa-nucleotides which contain terminal 3'-phosphate groups. 3. When EDTA is not present (pH 7.8 or 8.8) the plasma membrane preparation degrades both poly(A) and poly(U). With poly(A) the product is all nucleoside while with poly(U) as substrate most of the product is nucleoside, but also some oligonucleotides are produced. 4. The ribonuclease releases acid soluble products very slowly from high concentrations of poly(U) (mg/ml). 5. Uridine trinucleotide with and without a terminal 3'-phosphate group is degraded by rat liver plasma membrane. The trinucleotide diphosphate is rapidly hydrolyzed to nucleoside while the trinucleotide itself is slowly digested and yields intermediate products, including nucleoside.
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PMID:Effects of membrane ribonuclease and 3'-nucleotidase on the digestion of polyuridylic acid by rat liver plasma membrane. 0 89

The histidine C-2 proton NMR titration curves of ribonuclease S-peptide (residues 1 to 20) and S-protein (residues 21 to 124) are reported. Although S-protein contains 3 histidine residues, four discrete resonances are observed to titrate. One of these arises from the equivalent histidine residues of unfolded S-protein. The variation in area of the four resonances indicate that there is a reversible pH-dependent equilibrium between the folded and unfolded forms of S-protein, with some unfolded material being present at most pH values. Two of the resonances of the folded S-protein can be assigned to 2 of the histidine residues, 48 and 105, from the close similarity of their titration curves to those in ribonuclease. These similarities indicate a homology of portions of the folded conformation of S-protein to that of ribonuclease in solution. These results indicate that the complete amino acid sequence is not required to produce a folded conformation similar to the native globular protein, and they appear to eliminate the possibility that proteins fold from their NH2 terminus during protein synthesis. The low pH inflection present in the titration curve assigned to histidine residue 48 in ribonuclease is absent from this curve in S-protein. This is consistent with our previous conclusion that this inflection arises from the interaction of histidine 48 with aspartic acid residue 14, which is also absent in S-protein. The third titrating resonance of native S-protein is assigned to the remaining histidine residue at position 119. The properties of this resonance are not identical with either of the titration curves of the active site histidine residues 12 and 119 of ribonuclease. The resonance assigned to histidine 119 is the only one significantly affected on the addition of sodium phosphate to S-protein, indicating that some degree of phosphate binding occurs. In both the absence and presence of phosphate this curve also lacks the low pH inflection observed in the histidine 119 NMR titration curve in ribonuclease. This difference presumably arise from a conformational between ribonuclease and the folded S-protein involving a carboxyl group.
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PMID:Nuclear magnetic resonance titration curves of histidine ring protons. Ribonuclease S-peptide and S-proteins. 0 55

A finding was made that a species of ribonuclease is released into mycelial culture media when a wild-type strain of Neurospora crassa was grown on limiting amounts of phosphate. The ribonuclease activity in the fully derepressed state extends to about 60 to 100 fold of that in the repressed state. The synthesis of the ribonuclease was inhibited by the addition of rifampicin, cycloheximide or orthophosphate. Three molecular species of the ribonuclease were found. Two enzyme fractions showing larger molecular weights were suspected to be aggregates containing the enzyme showing the smallest molecular weight (molecular weight of 10 300). All three fractions showed pH optima of around 7, preferential hydrolysis of polyguanylic acid and poor hydrolysis of guanosine 2',3',-cyclic monophosphate. These characteristics were the same as those of ribonuclease N1, and it was suggested that ribonuclease N1 is a repressible extracellular enzyme. Mutations in the genes nuc-1 and nuc-2 caused loss of ability to derepress this enzyme, but heterokaryon between them partially restored the ability. The nuc-1 mutation was epistatic to the nuc-2 alleles which are partly constitutive in the ribonuclease production.
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PMID:Control of the formation of extracellular ribonuclease in Neurospora crassa. 0 54

Some physico-chemical properties, specificity and the character of action of rat liver nuclear ribonuclease are studied. The enzyme maximal activity was observed at pH 7.5--8.0, ionic strength 0.02--0.3, Mg2+ being necessary. Nuclease is an oligomer, having molecular weight is 160000--180000 daltons and containing separate associates. Purified enzyme is free of contaminating activities (polynucleotidephosphorylase, DNAse; 5'-nucleotidase, and alkaline phosphatases). It is shown to hydrolyse polyA and RNA for endonuclease type, degradation products being oligonucleotides terminating with 5'-phosphate and 3'-hydroxyl groups. RNAse hydrolyses all phosphodiester bonds in polynucleotides, developing no specificity to the nature of bases. Relative hydrolysis rate for different substrates decreased as follows: polyA greater than yeast RNA greater than polyC greater than polyU greater than 28S rRNA greater than greater than 18S rRNA greater than polyA-polyU. The enzyme may be classified as ribonucleate-5'-nucleotidehydrolase (EC 3.1.4.9.).
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PMID:[Nuclear ribonucleases and post-transcriptional changes of RNA. Specificity and other properties of rat liver nuclear endonuclease]. 1 31

An endonuclease which is active upon DNA exposed to ultraviolet light at a photoproduct other than thymine dimers has been extensively purified from Escherichia coli. The small (2.7 S) enzyme is active in the presence of EDTA, has a neutral pH optimum, and is inhibited by tRNA and 1 M NaCl. It has no detectable exonuclease, DNA-N-glycosidase, or ribonuclease activities. The enzyme also nicks duplex DNA exposed to OsO4, x-rays, or acid, but it does not act upon undamaged DNA or irradiated single-stranded DNA. The majority of sites of action in DNA exposed to ultraviolet light or OsO4 appear to be alkali-stable, but those in DNA exposed to x-rays or acid are not. The incisions created by the endonuclease contain 5'-phosphate termini. The enzyme is possibly the same as E. coli endonuclease III described by Radman (Radman, M. (1976) J. Biol. Chem. 251, 1438-1445), but it is distinguishable from the other endodeoxyribonucleases described from that organism.
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PMID:Endonuclease from Escherichia coli that acts specifically upon duplex DNA damaged by ultraviolet light, osmium tetroxide, acid, or x-rays. 1 1

Rat liver particulate neutral ribonuclease (EC 3.1.4.22) was extensively purified (up to 40000-fold). It is shown to be an endonuclease, specific for pyrimidine bases, hydrolysing 5'-phosphate ester bonds. The enzyme specificity, Km, pH optimum, stability in acid medium and thermal stability at high temperature are the same as those of rat pancreatic and serum ribonucleases. Like pancreatic and serum neutral ribonucleases, the hepatic enzyme is sensitive to the liver natural inhibitor. This inhibitor was purified 8000-fold; its association with ribonuclease follows zero-order kinetics. These identical properties for ribonuclease of rat liver, pancreas and serum support the hypothesis [Bartholeyns, Peeters-Joris & Baudhuin (1975) Eur. J. Biochem. 60, 385-393] of an extrahepatic origin for the liver enzyme, the plasma ribonuclease of pancreatic origin being taken up by endocytosis in the liver. Neutral ribonuclease activity was detected in all rat organs investigated; its distribution among tissues is different from the distribution of the natural ribonuclear inhibitor.
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PMID:Purification of rat liver particulate neutral ribonuclease and comparison of properties with pancreas and serum ribonucleases. 1 11

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

A recent conclusion that beef pancreas contained a molecular species of ribonuclease with intrinsically high activity at pH 4.5 has been found to be incorrect. The particular assay used in the earlier experiments gives anomalous results at acid pH in the presence of low concentrations of ions such as phosphate which was used during the fractionation. By turning to the more widely employed form of the perchloric acid precipitation assay, interference is avoided and the ribonuclease in beef pancreas is confirmed as consisting almost completely of the molecular species well-characterized as ribonuclease A. The clarification of the assay question permits a clear interpretation of the results of each step of the chromatographic purification procedure that led to the initial conclusion, including an artifact that arose when gel filtration was attempted with distilled water rather than with buffer.
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PMID:Explanation of the observation of pancreatic ribonuclease activity at pH 4.5. 1 66

Sodium acetate and sulphuric acid extracts of human epidermis can each be separated by chromatographic techniques into three or more fractions with ribonuclease activity. Eight of these fractions were compared with respect to molecular weight, pH activity profile, polyribonucleotide hydrolysis, and activity in the presence of low levels of spermidine. Sodium acetate and sulphuric acid extracts were also prepared from callus and from psoriatic lesions and compared with extracts from normal epidermis for their response to exogenous spermidine. All eight human epidermal ribonuclease fractions studied had an apparent molecular weight of 15,000 daltons. Seven of the ribonuclease fractions were optimally active at alkaline pHs (pH 7.3-7.6 in sodium phosphate and pH 8.I in Tris-HCl) while the eighth ribonuclease was most active at pH 5.6 in a citrate-phosphate buffer. All enzymes hydrolyzed polycytidylic acid and five also hydrolyzed polyuridylic acid. None hydrolyzed polyadenylic acid. Seven of the eight ribonucleases studied exhibited greater activity in the presence of added spermidine. The extracts from psoriatic scales showed markedly elevated ribonuclease levels which could not be raised further by the addition of spermidine.
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PMID:Epidermal nucleases. III. The ribonucleases of human epidermis. 2 41

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


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