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. Alkaline ribonuclease (pH optimum 7.6) was isolated from rye (Secale cereale L) germ cytosol and partially purified; the preparation was devoid of other nucleolytic activities. 2. The enzyme is a typical endonuclease hydrolysing all phosphodiester bonds in RNA, yielding ultimately purine and pyrimidine nucleoside 2',3'-cyclic phosphates and the corresponding 3'-phosphates. Upon extensive digestion of synthetic polyribonucleotides, pyrimidine, but not purine, nucleoside 3'-phosphates are formed. The enzyme does not hydrolyse synthetic purine cyclic nucleotides. 3. The enzyme does not depolymerize double-stranded complexes of poly(A) and poly(U). 4. Susceptibility to photooxidation and inhibition by 2-hydroxy-5-nitrobenzyl bromide and N-bromosuccinimide implies the involvement of tryptophan residue in the active centre of the enzyme.
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PMID:Alkaline ribonuclease from rye germ cytosol. 0 57

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

220-MHz NMR was used to observe the titration behavior of the 5 histidine residues in porcine pancreatic ribonuclease (ribonucleate pyrimidine-nucleotido-2'-transferase (cyclizing), EC 3.1.4.22) and a derivative prepared by removal of 80% of the attached carbohydrate from this glycoprotein. Resonances due to histidine C-2 protons were observed over the full pH range for 3 of the residues; such resonances for the remaining 2 histidine residues broadened out as the pH was increased. Resonances due to histidine C-4 protons were also observed for 2 of the residues. The titration curves for both proteins were identical within experimental error. Resonances were assigned by comparison with histidine NMR titrations in ribonucleases from other species. Histidine 105, immediately adjacent to the site of attachment of a heterosaccharide side chain, has a C-2 proton chemical shift and pK that are insensitive to the large alteration in the bulk of the carbohydrate side chain. The chemical shifts of the C-2 proton of histidine 48 and of the C-4 proton of histidine 80, histidine residues that are close to one another and to another heterosaccharide side chain, show a similar insensitivity. The observations are direct evidence in support of the thesis that the heterosaccharides in porcine ribonuclease project away from the surface of the protein into the solution environment.
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PMID:A comparison by 220-MHz NMR of histidine hydronium ion titrations in porcine pancreatic ribonuclease and an extensively deglycosylated derivative. 3 80

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

Rabbit globin complementary DNA made with RNA-dependent DNA polymerase (reverse transcriptase) was used as a template for in vitro synthesis of 32P-labeled RNA and deoxysubstituted RNA. The sequences of the nucleotides in most of the fragments resulting from combined ribonuclease T1 and alkaline phosphatase digestion have been determined. In addition, the 3' nearest neighbor was determined for several fragments resulting from digestion with T1 ribonuclease. The utility of the deoxysubstitution technique was demonstrated by the ease with which the sequences of pyrimidine-rich fragments could be determined. Many sequences thus determined were long enough to fit uniquely with the alpha- or beta-globin amino acid sequences. The positions of these fits were found to be clustered, leading us to believe that only certain regions of the complementary DNA are transcribed by Escherichia coli RNA polymerase. Other unique characteristics of RNA synthesis from a complementary DNA template include a high yield of free poly(A) and the fact that one must use low rather than high salt buffers to obtain transcripts of high molecular weight.
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PMID:Rabbit globin mRNA: analysis of T1 RNAse digestion fragments. 6 35

A substantial fraction (30--40%) of pulse-labeled RNA from exponentially growing cells of Bacillus brevis contains polyadenylate sequences, as measured by adsorption to oligo(dT)-cellulose. The weight-average length of poly(A) tracts obtained after digestion with pancreatic and T1 ribonucleases is 60 nucleotide residues. Susceptibility to degradation by snake venom phosphodiesterase after ribonuclease degradation indicates that the poly(A) sequences are located near the 3' ends of the RNA chains, but that in 40% of the material at least one internal pyrimidine nucleotide residue intervenes between the poly(A) tract and the 3'-hydroxyl terminus. These pyrimidine nucleotides consist of 65% cytidylate and 35% uridylate residues. In the remaining RNA chains, the poly(A) sequence is directly at the 3'-terminus, but the possibility cannot be excluded that a small fraction of this material may contain a 3'-hydroxyl terminal guanylate residue. The weight-average sedimentation coefficient of poly(A)-containing RNA is 12.5 S, corresponding to a polynucleotide chain length of 800--900 residues. This is in a size range expected for messenger RNA, a possibility which is also supported by the observation that pulse-labeled RNA has a considerably higher poly(A) content than long-term labeled RNA.
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PMID:Isolation and characterization of polyadenylate-containing RNA from Bacillus brevis. 21 Jul 91

A ribonuclease (ribonucleate 3-pyrimidine-oligonucleotidohydrolase, EC 3.1.4.22) was purified 8300-fold from soluble fraction of beef brain and its properties were investigated. The enzyme is an endonuclease capable of hydrolyzing tRNA, rRNA, poly(C), but shows no activity towards poly(U), poly(A), and poly(G). The preparation is free of deoxyribonuclease, non-specific phosphodiesterase and phosphomonoesterase activity. The enzyme has a pH optimum of 7.6, is not heat stable, has a molecular weight of 25 000, and has a K-m of 134 mu rRNA and K-m of 1600 mug poly(C) per ml.
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PMID:Purification of an alkaline ribonuclease from soluble fraction of beef brain. 23 61

A four-A electron density map was calculated for the monoclinic crystal of ribonuclease-S (RNase-S) based on two heavy-atom derivatives. Close geometrical similarity was found between the two crystallographically independent RNase-S molecules (called molecules ZA and ZB) in this crystal and that (called molecule Y) in the trigonal crystal. Using the rotational and translational parameters relating these three molecules, it was established that the crystallographic two-fold symmetry between the two molecules ZA in the monoclinic crystal was exactly identical to that between the two molecules Y in the trigonal crystal, suggesting the tendency of RNase-S molecules to associate in this way although the interaction is weak. The 4-A difference Fourier maps calculated for the monoclinic crystal established the following conclusions. (1) 4-Thiouridine-2'(3')-monophosphates binds to the B1 and R1 sites like other pyrimidine nucleoside-2'(3')-monophosphates as expected from previous spectrophotometric studies, but not to the B2 site even at the concentration of 20 mM. An attempt to visualize the photoproduct generated by irradiation of near-ultraviolet light in this complex failed. (2) p-Aminobenzoylglutamic acid, a fragment of folic acid, seems to bind to RNase-S with its benzene ring close to the B2 site and the alpha-carboxylate group close to the p1 site. The model is compatible with most of the chemical results obtained by Sawada et al. ((1977) Biochim. Biophys. Acta 479, 188-197).
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PMID:Crystal structure of monoclinic ribonuclease-S at 4 A resolution. The mode of binding of 4-thiouridylic acid and a fragment of folic acid, p-aminobenzoylglutamic acid. 30 95

A ribonuclease has been extracted from bat liver and purified. From polyacrylamide gel electrophoresis, it was found that there is only one molecular weight unit in this enzyme and this has a molecular weight of about 28,000. This enzyme was found to hydrolyse both purine and pyrimidine polynucleotides (e.g. polyadenylic acid and polycytidylic acid respectively). Hydrolysis of polyadenylic acid was found to be faster than that of polycytidylic acid.
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PMID:Partial purification and characterisation of bat liver ribonuclease. Hydrolysis of purine and pyrimidine polynucleotides by bat liver RNase. 55 31

Red kangaroo (Macropus rufus) ribonuclease was isolated from pancreatic tissue by affinity chromatography. The amino acid sequence was determined by automatic sequencing of overlapping large fragments and by analysis of shorter peptides obtained by digestion with a number of proteolytic enzymes. The polypeptide chain consists of 122 amino acid residues. Compared to other ribonucleases, the N-terminal residue and residue 114 are deleted. In other pancreatic ribonucleases position 114 is occupied by a cis proline residue in an external loop at the surface of the molecule. Other remarkable substitutions are the presence of a tyrosine residue at position 123 instead of a serine which forms a hydrogen bond with the pyrimidine ring of a nucleotide substrate, and a number of hydrophobichydrophilic interchanges in the sequence 51-55, which forms part of an alpha-helix in bovine ribonuclease and exhibits few substitutions in the placental mammals. Kangaroo ribonuclease contains no carbohydrate, although the enzyme possesses a recognition site for carbohydrate attachment in the sequence Asn-Val-Thr (62-64). The enzyme differs at about 35-40% of the positions from all other mammalian pancreatic ribonucleases sequenced to date, which is in agreement with the early divergence between the marsupials and the placental mammals. From fragmentary data a tentative sequence of red-necked wallaby (Macropus rufogriseus) pancreatic ribonuclease has been derived. Eight differences with the kangaroo sequence were found.
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PMID:The amino-acid sequence of kangaroo pancreatic ribonuclease. 65 39


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