Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.4 (ribonuclease)
 6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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 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

Poly(A)-containing mRNAs labeled with [methyl-3H]methionine were isolated from nucleated erythroid cells obtained from the spleens of anemic mice. The RNAs were further separated into non-globin poly(A)-containing RNAs and highly purified globin mRNA by globin cDNA-cellulose affinity chromatography. DEAE-Sephadex column chromatography of the T2 ribonuclease digestion products of the cDNA-purified globin mRNA fraction yielded methylated resistant fragments with charges of -4.7 (Cap 1) and -5.3 (Cap 2). Digestion of the non-globin RNA fraction revealed a similar pattern with the addition of a methylated mononucleotide identified as 6-methyladenosine at -2 charges. Alkaline phosphatase treatment of the T2 resistant fragments reduced their charges by approximately 2, which is consistent with the removal of one terminal phosphate. Treatment of the globin T2 and alkaline phosphatase-resistant fragments withpenicillium P1 nuclease and alkaline phosphatase yielded a P1-resistant core structure in both fragments. In addition to the core, 2'-O-methylcytidine (Cm) was released from the more negatively charged globin fragment. The P1-resistant cores of the cap structures eluted from DEAE-Sephadex with the known standard m2G5'ppp5'Am and were found to be pyrophosphatase-sensitive establishing a 5'-5'-triphosphate linkage. The pyrophosphatase and alkaline phosphatase digestion products of the globin Cap 1 and Cap 2 core structures were analyzed by high voltage electrophoresis and paper chromatography and found to be 7-methyiguanosine (m7G) and the dimethylated nucleoside 6-methyl-2'-O-methyladenosine (N6mAm). A small amount of the singularly methylated adenosine, 2'-O-methyladenosine (Am) was also observed. The predominant sequences of the methylated nucleosides in the globin cap structures are therefore m7G5'ppp5'N6mAm and m7G5'ppp5'N6mAmpCm.
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PMID:Methylated nucleosides in globin mRNA from mouse nucleated erythroid cells. 83 41

Total cellular RNA was isolated from the ciliate protozoan Paramecium aurelia by pH 9.5 chloroform/octanol extraction. Passage of this RNA through an oligo(dT)-cellulose column in 0.5 M NaCl resulted in 2--3% binding, indicating the presence of polyadenylic acid sequences. These polyadenylic acid regions were estimated to be 250-500 nucleotides in length, based on their resistance to ribonuclease degradation. The oligo(dT)-cellulose bound RNA sedimented at 14--25 S in sodium dodecyl sulphate/sucrose gradients. The base composition of this RNA is similar to the base composition of the DNA. This RNA was also actively translated into protein by an in vitro protein synthesizing system isolated from wheat germ. Translation was optimal under conditions similar to those used for mammalian mRNA translation. In addition, translation of the P. aurelia oligo(dT)-cellulose bound RNA was inhibited 80% by the analog 7-methylguanosine-5'-phosphate, suggesting the presence of a 5'-capped terminus.
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PMID:Isolation and characterization of mRNA from Paramecium aurelia. 88 13

The rate of hydrolysis of protein-methyl ester, the enzymatic product of S-adenosylmethionine: protein-carboxyl methyltransferase (EC.2.1.1.24) acting on oxidized ribonuclease, was measured at pH 7.1 and 8.6 at 37 degrees C. The half-life of the hydrolysis of the ester is 25 min at pH 7.1, and 4 min at 8.6. The rate of hydrolysis of the enzymatically formed esters at pH 7.0, in 0.1 M phosphate buffer, was about 25 times faster than that of esters formed chemically by reaction with methanol in HCl. The lability of the enzymatically synthesized protein-methyl ester suggests that the esterification is specific to sites such that ionization of neighboring amino acid side chains enhances the rate of the hydrolysis.
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PMID:Labile protein-methyl ester: comparison between chemically and enzymatically synthesized. 95 34

The fluorescence lifetimes and relative quantum yields of several derivatives of tyrosine are reported. The quenching of the fluorescence of these compounds by phosphate, caesium and iodide ions has been investigated; the encounter rate constants, calculated from the quenching parameters and lifetimes, show a clear dependence on the charges borne by the quenchers and fluorophores. The ratio of the Stern-Volmer constants of iodide and caesium, ions of similar size, defines an electrostatic parameter sensitive to the charge of the fluorophore which can be evaluated without knowledge of the fluorescent lifetimes. The mean of the encounter rate constants for caesium and iodide ions defines a rate constant which is largely charge-independent and is used to establish a steric parameter. The two parameters are used to investigate the tyrosine environment in bovine ribonuclease A (EC 3.1.4.23) and Erwinia carotovora L-asparaginase (EC 3.5.1.1). The quantum yield of L-asparaginase (0.12) is very high for a class A protein and may be associated with the absence of disulphide bridges. There was no evidence for more than one type of tyrosine residue from the quenching experiments with either enzyme, an observation which is attributed to efficient energy transfer amongst tyrosine residues. At pH values close to the isoelectric points of the enzymes the electrostatic parameter suggests that the environment of the quenchable tyrosines in L-asparaginase is somewhat more positive than in ribonuclease. In 1% sodium dodecyl sulphate the tyrosine environment of L-asparaginase becomes markedly negative as expected. The steric parameter indicates a lower accessibility of the tyrosine residues in L-asparaginase than in ribonuclease; an illustrative calculation is provided linking the steric parameter with the number of exposed tyrosine residues by taking into account the greater collision frequency of the larger protein molecules and the encounter distance for quenching determined from charge effects on the quenching of the model compounds. The calculation suggests that three tyrosyl residues are accessible in ribonuclease, in good agreement with other studies, but in L-asparaginase the number increases from 0.4 at pH 5.73 to 0.8 at pH 9.16 suggesting a loosening of the enzyme structure at high pH.
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PMID:An investigation of the electronic and steric environments of tyrosyl residues in ribonuclease A and Erwinia carotovora L-asparaginase through fluorescence quenching by caesium, iodide and phosphate ions. 98 70

With the use of a precursor to Escherichia coli tRNA-Tyr as a substrate, we have detected and partially purified a novel endoribonuclease from the cytoplasm of human KB tissue culture cells. This activity, which we have called RNase NU, cleaves the tRNA precursor at two sites in that part of the molecule which is not included in the mature tRNA sequence and which is normally degraded in vivo. In keeping with this observation, we have found that, of a variety of substrates tested, only those which are unstable in vivo are attacked by RNase NU. RNase NU can be purified from the 0.2 M NH4Cl wash of ribosomes followed by ammonium sulfate fractionation and DEAE-Sephadex chromatography. RNase NU cleaves RNA to create 3'-phosphate-terminated oligonucleotides. It has a pH optimum near 8.0, requires either a monovalent cation (NH4+ is most efficient) or Ca-2+ for optimal activity, and is inhibited by 0.1 M PO4-3-. In the course of purifying RNase NU we have detected and studied the intracellular distribution of other ribonuclease activities in human KB cells.
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PMID:Partial purification and properties of an endoribonuclease isolated from human KB cells. 108 59

A rapid and simple synthesis of pppGpN type /N equals C, U or A/ diribonucleotide derivatives is described by coupling guanosine 2', 3'-cyclic phosphate 5'-triphosphate with the appropriate ribonucleoside in the presence of ribonuclease T-1.
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PMID:Synthesis of pppGpN type dinucleotide derivatives: the 5' end sequence of some RNAs. 109 17


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