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:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rate constants and Km for the hydrolysis of the optically active nonglycosidic analogues of the CpA and C greater than p catalysed by RNase A and RNase BS-I were measured. The rate of hydrolysis of the model substrates in 10(5) and 10(3) slower that for the appropriate dinucleoside phosphate and nucleoside cyclophosphate. However, substitution of the relatively rigid ribofuranose ring with flexible alifatic chains is accompanied by little variation in binding constants. The analyses based on the single substrate system indicate that the observed difference in rate constants must be accounted for by a difference between the binding of the substrates in the transition state to the RNase active site. Consequently, the "rigidity" of the ribose rings in RNA leads to large decreases in the free energy of activation for the reactions catalysed by RNases.
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PMID:[Role of the ribose residue of substrates in reactions catalyzed by ribonuclease]. 68 97

(1) N2,N2,7-Trimethylguanosine, not previously detected as a component of plant RNA, is shown to be present in the RNA which is isotopically labelled when dry wheat embryos imbibe water in a medium that contains[methyl-3H]methionine. (2) N2,N2,7-Trimethylguanosine and 7-methylguanosine are released as part of "capped" oligonucleotides when the isotopically labelled RNA from imbibing wheat embryos is subjected to hydrolysis by RNase T2. (3) By way of contrast with the "capped" RNA of animal cells, 5'-terminal "cap" structures (m7Gppp- and m32,2,7 Gppp-) in the "capped" RNA from the higher plant organism are not bonded to pneultimate O2'-methylnucleoside constituents. (4) In an allied study, it has been found that recovery of poly (A)-rich RNA from dry wheat embryos depends on the inclusion of sodium dodecyl sulphate (SDS) in phosphate-buffered (pH 6.8) phenolic emulsions. By way of contrast, recovery of poly (A)-rich RNA from dry wheat embryos does not depend on the inclusion of SDS in Tris (hydroxymethyl) aminomethane buffered (pH 9.0) phenolic emulsions.
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PMID:Wheat embryo ribonucleates. XII. Formal characterization of terminal and penultimate nucleoside residues at the 5'-ends of "capped" RNA from imbibing wheat embryos. 68 62

When pancreatic DNase I is used as a specific biochemical reagent in the preparation of nuclear ribonucleic acids or nuclear proteins, freedom from contaminating ribonucleases or proteases is an important property of the enzyme preparation. A simple one-step procedure has been developed to effect complete removal of trypsin, chymotrypsin, and chymotrypsinogen by a combination of affinity chromatography and salting-out adsorption on lima bean protease inhibitor coupled to Sepharose (a column (0.9 X 60 cm) operated in series with a regeneratable 1-ml bed). Commercial preparations of DNase (about 10 mg) give a quantitative yield of the enzyme that is protease-free as evidenced by full stability for more than 10 days at pH 8 and 37 degrees C even in the absence of the protecting action of Ca2+. Removal of the last traces of RNase has been accomplished by affinity chromatography on a column (0.4 X 72 cm) of 5'-(4-aminophenyl-phosphoryl)-uridine 2'(3')-phosphate-Sepharose; the product is a highly active DNase that gives no detectable hydrolysis of RNA by assay on radioactive substrates.
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PMID:Preparation of protease-free and ribonuclease-free pancreatic deoxyribonuclease. 70 Dec 44

In the presence of Mg(2+) and a specific dinucleotide primer (ApG or GpG), the influenza virion transcriptase synthesizes the eight discrete segments of complementary RNA (cRNA) containing polyadenylic acid (Plotch and Krug, J. Virol. 21:24-34, 1977). Virions were examined for their ability to cap and methylate cRNA containing di- or triphosphorylated 5' termini. By using the primers ppApG, pppApG, or ppGpG, viral cRNA was synthesized in vitro with [alpha-(32)P]-GTP and S-[methyl-(3)H]adenosylmethionine as labeled precursors. DEAE-Sephadex chromatography of the RNase T2 digest of the cRNA product demonstrated no (3)H incorporation at all and the absence of a (32)P-labeled cap structure. The 5' terminus of ppApG-primed cRNA could be capped and methylated by enzymes from vaccinia virus, indicating that the two 5'-terminal phosphates derived from the primer were preserved in the product cRNA. The cap structure formed by the vaccinia enzymes and released by RNase T2 digestion as m(7)GpppA(m)pGp was radioactively labeled at its 3'-terminal phosphate only when [alpha-(32)P]CTP was used as the labeled precursor during transcription. This indicates that the 5'-terminal sequence of the cRNA is ppApGpC and that, therefore, ppApG most probably initiates transcription exactly at the 3' GpCpU(OH) terminus of the virion RNA templates. Virions were also tested for their ability to cap and methylate ppApG in the absence of transcription. No such activities were detected, whereas under the same conditions the vaccinia virus enzymes successfully capped and methylated this compound. Consequently, these experiments, together with those reported earlier, have not detected in influenza virions any capping and methylating enzymes active on the 5'-initiated termini of viral cRNA chains synthesized in vitro, whether these termini possess one, two, or three phosphates. Some mechanism for capping and methylation of viral cRNA must, however, exist, because the viral mRNA (cRNA) synthesized in the infected cell contains 5'-terminal methylated cap structures (Krug et al., J. Virol. 20:45-53, 1976). Possible mechanisms are discussed.
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PMID:Absence of detectable capping and methylating enzymes in influenza virions. 70 57

Evidence is presented for the presence of a protein covalently bound to the 5' termini of both M and B RNA components of CPMV. The protein is found to be linked in both cases to the 5' phosphate of the dinucleotide pUpAp, derived by ribonuclease digestion of the RNA. The intact protein is not required for infectivity or for in vitro translation of the RNA in cell-free extracts.
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PMID:A protein linked to the 5' termini of both RNA components of the cowpea mosaic virus genome. 74 88

tRNA3Met, one of the non-initiating methionine-specific tRNAs in brewer's yeast was purified from bulk tRNA labelled with [32P]phosphate by two column chromatographic steps. The primary structure of this tRNA was determined by the usual fingerprinting technique. Analyses of the isolated nucleotides and oligonucleotides from digests with pancreatic and T1 ribonucleases were in good agreement and stated that tRNA3Met consists of 76 nucleotide residues including 13 minor nucleotides. Overlaps from which the complete sequence could be deduced were derived from the analyses of 15 fragments obtained by partial digestion with T1 ribonuclease.
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PMID:The primary structure of a non-initiating methionine-specific tRNA from brewer's yeast. 78 36

Lipopolysaccharides, extracted by phenol-water from five strains fo Neisseria gonorrhoeae, were purified by treatment with ribonuclease followed by multiple washes. These preparations were fatal to mice when administered in submicrogram amounts with actinomycin D, the LD50 values varying from 4 to 16 mug/kg. Analyses showed that all preparations contained glucose, galactose, glucosamine, heptose, 2-keto-3-deoxyoctonic acid and phosphate. All the lipopolysaccharides contained the same fatty acids, namely beta-OH-10:0, beta-OH-12:0, beta-OH-14:0, 12:0, 14:0,16:0, 16:1, 18:0 and 18:1. We were unable to detect significant differences between the lipopolysaccharides of virulent and avirulent gonococci or between penicillin-sensitive and resistant strains. Gonococcal lipopolysaccharides appeared to lack O-antigen side chains.
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PMID:Studies on lipopolysaccharides isolated from strains of Neisseria gonorrhoeae. 80 76

A mutant cell line (IF2) derived from the mouse myeloma MOPC 21 has been used for the isolation and sequence analysis of H-chain mRNA. The IF2 cells synthesise an H-chain of reduced size in which the CH1 homology region is missing. Sizing of the IF2 H-chain mRNA and wild-type H-chain mRNA revealed that the deletion is expressed at the mRNA level. The mutant H-chain mRNA sedimented at 16-S, enabling effective resolution from 18-S ribosomal RNA. In experiments using IF2 cells labelled with [32P]phosphate, the 16-S mRNA was purified by oligo(T)-cellulose chromatography. Polyacrylamide gel analysis of the poly(A)-containing fraction showed the presence of a single radioactive band. Comparison of the mobility of this band relative to markers of known molecular weight revealed that the molecule contained about 1600 nucleotides. Digestion of the 32-P-labelled mRNA with T1 ribonuclease and two-dimensional fractionation of the resulting oligonucleotides yielded a 'finger-print' suitable for a preliminary sequence analysis. By using the established amino acid sequence of the IF2 H-chain and a knowledge of the genetic code, 14 oligonucleotides were assigned within the constant region and four within the variable region of the IF2 H-chain. This sequence data accounts for 19.5% of the coding region. Several other oligonucleotides, which could not be assigned within the coding region but which occurred in approximately molar yield, have also been partially characterised. These oligonucleotides are presumably derived from the untranslated regions of mRNA.
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PMID:Purification and sequence analysis of the mRNA coding for an immunoglobulin heavy chain. 81 96

The Mg2+ precipitation procedure of R. D. Palmiter ((1974) Biochemistry 13, 3606) has been used for preparative scale isolation of polysomes from Ehrlich ascites mitochondria. Digitonin-washed metochondria used for isolating the polysomes contain no detectable reduced nicotinamide adenine dinucleotide phosphate-cytochrome c reductase and over 200-fold reduced hexokinase activity. The mitochondrial polysomes exhibit a heterogeneous sedimentation and appear to contain highly aggregated particlses ranging over hexamers. These polysomes are sensitive to RNase, (ethylenedinitrilo)tetraacetic acid and puromycin. Mitochondrial polysomes are active in portein synthesis when supplied with supernatant enzymes from the homologous mitochondrial source or from Escherichia coli. Cytoplasmic enzymes, however, appear to be completely inactive. Protein synthesis by mitochrondrial polysomes is sensitive to chloramphenicol and resistant to cycloheximide and emetine. The procedure yields particles containing intact rRNAs. The extent of cytoplasmic RNA contaminating the total mitochondrial RNA or mitochondrial polysomal RNA has been estimated to be negligible.
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PMID:Messenger ribonucleic acid metabolism in mammalian mitochondria. Isolation and characterization of polyribosomes from Ehrlich ascites mitochondria. 82 18

The cells of Escherichia coli strain CP 78 were labeled with [32P]orthophosphate and the total radioactive RNA was prepared from the cells. The mRNA that codes for a structural lipoprotein in the outer membrane was purified from the total RNA by three successive electrophoreses on polyacrylamide slab gels, twice at pH 8.3 and once at pH 3.5 in 7 M urea. Approximately 0.002% of the total radioactive phosphate used was incorporated into the fraction containing the most purified mRNA. The two-dimensional fingerprint of the T1 ribonuclease digest of the 32P-labeled mRNA showed that the purity of the mRNA was as high as 90%. A preliminary sequence analysis was carried out on the T1 ribonuclease oligonucleotides which had been separated by the fingerprinting procedure. By using the established amino acid sequence of the lipoprotein and the genetic code, three relatively long oligonucleotides were assigned to code for three different parts of the lipoprotein. From these data, the present RNA fraction was identified as the lipoprotein mRNA. From the analysis of the T1 ribonuclease oligonucleotides, the mRNA was estimated to be 360 +/- 10 nucleotides in length. Although the length of the mRNA was enough to code for 2 lipoprotein molecules, T1 ribonuclease digestion of the mRNA yielded only 1 mol/mol of mRNA of the individual oligonucleotides assigned to parts of the amino acid sequence of the lipoprotein. This suggests that the mRNA codes for only 1 molecule of the lipoprotein. It was also found that the mRNA has no polyadenylate sequence at the 3' end.
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PMID:Isolation and identification of the messenger ribonucleic acid for a structural lipoprotein of the Escherichia coli outer membrane. 82 86


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