Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.5 (RNase)
 17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The complexed 70S ribosomes (monosomes) that accumulate in Escherichia coli after an energy source shift-down were examined in an electron microscope. In all cases, the ribosomes lie at or near one end of a ribonucleic acid (RNA) strand. This messenger RNA (mRNA) has a mean length of 168 nm and a length-average length of 200 nm, sufficient to code for polypeptides of a weight-average molecular weight of 20,000. The length distribution indicates that these strands are a reasonable representation of the population of monocistronic mRNA's of E. coli. The mRNA strands disappear entirely upon digestion with pancreatic ribonuclease, phosphodiesterase I, or polynucleotide phosphorylase. The susceptibility to digestion by 3'-exonucleases indicate that the ribosomes lie at the 5' end of the mRNA strands. These results are consistent with the hypothesis that down-shifted cells have a translational defect at a point subsequent to the binding of ribosomes to mRNA but prior to the formation of the first peptide bond, such that ribosomes remain bound at or near their points of initial attachment to mRNA.
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PMID:Association of messenger ribonucleic acid with 70S monosomes from down-shifted Escherichia coli. 17 81

Poly(A) polymerase was extracted from isolated nuclei of rat liver and a rapidly growing solid tumor (Morris hepatoma 3924A). The enzyme from each tissue was purified by successive chromatography on DEAE-Sephadex, phosphoecllulose, hydroxyapatite and QAE-Sephadex. Purified enzyme from both liver and tumor was essentially homogeneous as judged by polyacrylamide gel electrophoresis. Under nondenaturing conditions, enzyme activity corresponded to visible protein and, upon denaturation, a single polypeptide was detected. The enzymes had absolute requirements for Mn2+ as the divalent ion, ATP as the substrate and an oligonucleotide or polynucleotide as the primer. Both enzymes were inhibited by sodium pyrophosphate, N-ethylmaleimide, Rose Bengal, cordycepin 5'-triphosphate and several rifamycin derivatives. The reactions were unaffected by potassium phosphate, alpha-amanitin and pancreatic ribonuclease. However, the liver and hepatoma enzymes differed from each other with respect to apparent Km, primer saturation levels and sensitivity to pH changes. The most striking differences between the enzymes were in their calculated molecular weights (liver, 48000; hepatoma, 60000) and amino acid compositions. Finally, the level of the hepatoma enzyme relative to that of the liver enzyme was at least 1.5-fold higher when expressed per mg DNA.
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PMID:Nuclear poly(A) polymerase from rat liver and a hepatoma. Comparison of properties, molecular weights and amino acid compositions. 18 50

Pig rotavirus was purified from faeces. The RNA from this virus was resistant to pancreatic ribonuclease, indicating that it is double-stranded. When electrophoresed on polyacrylamide-agarose gels, pig rotavirus RNA migrated as 9 bands comprised of 11 or 12 RNA segments with a total mol. wt. of approx. 11 X 10(6). Co-electrophoresis experiments revealed that the RNAs from the pig virus and two isolates of the calf rotavirus were indistinguishable.
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PMID:Characterization of pig rotavirus RNA. 18 25

3-SLHis-105-RNase A is an active derivative of ribonuclease A (RNase A) spin-labeled at the 3 position of the imidazole ring of histidine-105. The spin-labeled enzyme has been modified by urea denaturation, reduction, reduction-carboxymethylation, performic acid oxidation, and digestion with proteolytic enzymes in order to monitor changes in the geometry of the protein by changes in the electron paramagnetic resonance (EPR) spectrum of the nitroxide spin-label probe. The results of these experiments indicate that the spin-label attached to histidine-105 of RNase A is sensitive to modifications affecting the conformational integrity of the molecule and to the reconstituting effects of various active-center ligands.
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PMID:Spin-labeled ribonuclease A. Effects of chemical, enzymatic, and physical modifications on enzyme conformation. 20 8

A dialysable low-molecular-weight factor capable of affecting in vitro properties of macrophages was extracted from four different mouse tumors. This factor not only modulates closely related properties of peritoneal macrophages such as spreading and migration but also inhibits lipopolysaccharde-induced tumoricidal activity of these cells. It can be extracted not only from tumor tissues but also from tumor cells grown in vitro. The appearance of this factor is unique to tumors and it is not present in detectable quantities in normal tissues. The factor from one of the tumors, Lewis lung carcinoma, was purified extensively and the partially purified factor retains all the above effects on macrophages. It is not sensitive to pronase or a mixture of bovine spleen phosphodiesterase II, E. coli alkaline phosphatase and pancreatic ribonuclease. The factor is lipid-like in character and it is soluble in both organic solvents and aqueous media. It has ionizable group(s) and is anionic at neutral pH but non-ionic under acidic conditions.
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PMID:Characteristics of a low-molecular-weight factor extracted from mouse tumors that affects in vitro properties of macrophages. 22 Jan 97

The reassignment of the 1H NMR C-2 histidine signals of the bovine pancreatic ribonuclease A has required a revision of the 1H NMR data on the role of the different histidines in their interaction with the Cu2+. The results of our measurements carried out at p2H 5.5 and 7.0 reduce the importance of His-12 as main site of interaction. At p2H 5.5 a very strong binding site involves His-119, while a weaker one contains certainly His-105. On the contrary, at p2H 7.0 the histidines 105 and 119 seem to possess binding constants of the same order of magnitude and in addition they provide stronger ligands for the Cu2+ than His-12. The comparison with X-ray data in the crystal shows numerous analogies. Finally, preliminary results on the competitive inhibition effect between the Cu2+ and 2',3'-cytidine monophosphoric acid are discussed.
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PMID:1H NMR study on the interaction of cupric ion with ribonuclease A. 23 64

Evidence is presented that ovine pancreatic ribonuclease, a protein strictly homologous to bovine RNAase A but with one positive charge less, has a definite 'destabilizing' activity (quite similar to that of the bovine enzyme) on double-stranded DNA. This action of sheep pancreas RNAase has been measured by differential spectrophotometry and determining the thermal-transition profiles of the protein-DNA complexes.
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PMID:[DNA-protein interactions. Destabilizing activity of sheep pancreatic RNAase]. 23 46

1, 2-Cyclohexanedione reacts specifically with the guanidino group of arginine or arginine residues at pH 8 to 9 in sodium borate buffer in the temperature range of 25-40 degrees. The single product, N-7, N-8-(1,2-dihydroxycyclohex-1,2-ylene)-L-arginine (DHCH-arginine) is stable in acidic solutions and in borate buffers (pH 8 to 9). DHCH-Arginine is converted to N-7-adipyl-L-arginine by periodate oxidation. The structures of the two compounds were elucidated by chemical and physicochemical means. Arginine or arginyl residues can be regenerated quantitatively from DHCH-arginine by incubation at 37 degrees in hydroxylamine buffer at pH 7.0 FOR 7 TO 8 hours. Analysis of native egg white lysozyme and native as well as oxidized bovine pancreatic RNase, which were treated with cyclohexanedione, showed that only arginine residues were modified. The utility of the method in sequence studies was shown on oxidized bovine pancreatic ribonuclease A. Arginine modification was complete in 2 hours at 35 degrees in borate buffer at pH 9.0 with a 15-fold molar excess of the reagent. The derived peptides showed that tryptic hydrolysis was entirely limited to peptide bonds involving lysine residues, as shown both by two-dimensional peptide patterns and by isolation of the resulting peptides. The stability of DHCH-arginyl residues permits isolation of labeled peptides.
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PMID:Reversible modification of arginine residues. Application to sequence studies by restriction of tryptic hydrolysis to lysine residues. 23 32

An alkaline ribonuclease (pH optimum near 8) has been purified from whole beef brains and found to have a base specificity like that of bovine pancreatic ribonuclease, but in most other respects to be distinguishable from the enzymes of bovine pancreas, semen, or brain nuclei. The preparation appears homogeneous in sedimentation equilibrium and probably so in polyacrylamide gel electrophoresis under normal or dissociating conditions. Sedimentation equilibrium and SDS gel electrophoresis both indicate a molecular weight of 2.4-2.6 times 10-4, and tryptic and chymotrypic peptide patterns are consistent with a protein of this size. No dissociation into subunits has been attained. The enzyme is not precipitated by antiserum to pancreatic ribonuclease, although its activity is inhibited by this antiserum with low efficiency. In comparisons of the hydrolysis of RNA the brain enzyme was found to have a similar specificity to pancreatic RNase, but to have a loser Km for RNA and to produce significantly different oligonucleotides upon partial hydrolysis of bacteriophage RNA, suggesting differences in the mechanism of substrate recognition. In contrast, nuclease inactivation by iodoacetate at pH 5.5 is indistinguishable for pancreatic or purified brain RNase.
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PMID:Characterization of a ribonuclease from bovine brain. 23 53

A poly(U) polymerizing enzyme has been found in healthy and tobacco mosaic virus-infected tobacco leaves and has been partially purified by affinity chromatography on a gel prepared from agarose with chemically coupled RNA. The enzyme is stimulated by Mn-2+ and dependent on a polynucleotide, preferentially poly(A). The synthesis proceeds optimally at pH 7.6 and 25 degrees C. The enzyme is highly specific for UTP and is inhibited by other ribonucleoside triphosphates. The product was partly sensitive to pancreatic ribonuclease. The synthetic reaction is inhibited in the presence of pyrophosphate but insensitive to 10 mM orthophosphate and high levels of cordycepin, rifampicin and actinomycin D. A molecular weight of about 40,000 has been estimated by sucrose gradient analysis and partition cell ultracentrifugation.
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PMID:A poly(U) polymerase in tobacco leaves. 23 94


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