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)

Chromatography on Concanavalin A sepharose is a simple procedure for partial purification of spleen phosphodiesterase. This procedure removes much, but not all, of the ribonuclease activity found as contaminant in most spleen phosphdisterase preparations.
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PMID:A rapid method for preparation of calf spleen exonuclease. 20 Aug 94

Poly(A)-containing messenger RNA isolated from rabbit reticulocytes as estimated by periodate oxidation and condensation with [3H]isoniazid has two oxidizable end groups per molecule of mol. wt. 220000. When the mRNA is subjected to stepwise degradation by beta-elimination, only one oxidizable end-group is found. This indicates that one of the 2',3' hydroxyl end-groups is linked through the normal 3'--5' phosphodiester bond, but that the other is linked in such a way that after stepwise degradation no new 2',3 hydroxyl group is revealed. This structure could be a 5'-linked 5'-phospho di- or tri-ester. On digestion with ribonuclease the isoniazid-labelled RNA produced oligonucleotide hydrazones consistent with a poly(A) sequence at the 3' end plus fragments that are not found after stepwise degradation. These fragments have a charge of --6 and --8 from pancreatic ribonuclease or --7 from ribonuclease T1 digestion. These charges are changed to --3.4 and --4.1 after pancreatic ribonuclease, ribonuclease T2 and alkaline phosphatase digestion. methyl-3H-labelled-poly(A)-containing RNA isolated from late erythroid cells contain a methyl-labelled fragment resistant to endonuclease and phosphodiesterase II digestion. After digestion with phosphodiesterase I this fragment produces methyl-3 H-labelled nucleotides with the electrophoretic mobility of pm7G and pAm. It is concluded that globin mRNA has the 5' sequences m7G(5')ppp'AmpYpGp ... and m7G(5')pppAmpApGpYp.
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PMID:The nature of the 5'-linked 5' nucleotide sequence at the 5' end of rabbit globin messenger ribonucleic acid. 94 25

Poly(A)-specific ribonuclease was co-purified with poly(A) polymerase from Vigna unguiculata seedlings. Both activities were separated into two forms (enzymes I and II) by a final hydrophobic column chromatography. The enzyme I preparation, which was homogeneous as examined by SDS/PAGE, had both poly(A) polymerase and poly(A)-specific ribonuclease activities. The antibody raised to the enzyme I preparation precipitated both enzyme activities. These indicate that a single polypeptide (Mr 63,000) is responsible for both poly(A)-polymerizing and poly(A)-hydrolyzing activities. The poly(A)-specific ribonuclease was a 3'-exonuclease specific to single-stranded poly(A), forming 5'AMP as the sole reaction product. The hydrolytic activity required either Mn2+ or Mg2+ with different optimum concentrations, whereas the polymerizing activity required Mn2+ but not Mg2+. ATP and PPi had little or no effect on the poly(A)-specific ribonuclease activity.
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PMID:Poly(A) polymerase from Vigna unguiculata seedlings. A bifunctional enzyme responsible for both poly(A)-polymerizing and poly(A)-hydrolyzing activities. 255 12

1. Different reaction steps involved in protein synthesis were studied in skeletal muscles from control and myopathic hamsters. 2. There was no difference between partially purified aminoacyl-tRNA synthetases from myopathic and control animals in yield or catalytic activity, as tested with exogenous deacylated tRNA. 3. However, isolated deacylated tRNA from myopathic muscle was aminoacylated by these synthetases to a lesser extent than that derived from control muscle. 4. Addition of deacylated tRNA isolated from control muscle improved the performance of pH5 enzymes from myopathic muscle in polypeptide synthesis on homologous polyribosomes; tRNA isolated from myopathic animals did not. 5. Preparation of extracts from both types of animals in the presence of the ribonuclease-absorbent bentonite led to an increased capacity of endogenous tRNA to accept amino acids in pH5 enzymes prepared from normal and abnormal tissue, but the difference between the two systems remained the same. 6. Total tRNA nucleotidyltransferase activity, tested with twice-pyrophosphorolysed rat liver tRNA, was identical in both extracts. 7. Added tRNA nucleotidyltransferase incorporated more AMP and CMP into endogenous tRNA with the pH5 enzyme from myopathic muscle than with that from control muscle. 8. Preincubation of deacylated tRNA from myopathic muscle with ATP, CTP and tRNA nucleotidyltransferase more than doubled its subsequent aminoacyl-acceptor activity, and halved the extent of the defect relative to aminoacylation of control tRNA similarly treated. Endogenous tRNA in pH5 enzyme preparations behaved likewise. 9. It is suggested that a 3'-exonuclease in myopathic muscles attacks tRNA molecules in such a way that some of them remain substrates for tRNA nucleotidyltransferase, which may incorporate into RNA not only AMP and CMP, but also GMP. 10. Cell-free protein synthesis in preparations from myopathic hamster muscles is limited by the supply of intact tRNA molecules.
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PMID:Evidence for defective transfer ribonucleic acid in polymyopathic hamsters and its inhibitory effect on protein synthesis. 472 37

The nascent DNA synthesized by permeable cells of Bacillus subtilis in the presence of 5'-mercurideoxycytidine triphosphate and 2',3'-dideoxyATP has been isolated and characterized. The newly synthesized DNA was isolated free from other cellular nucleic acids by affinity chromatography on thiol-substituted agarose. The number average chain length of the nascent DNA synthesized in one minute at 25 degrees C was 33 nucleotide residues, due to the chain-terminating action of 2',3'-dideoxyATP. Several lines of evidence indicated that at least 90% of the DNA thus isolated carried a terminally phosphorylated RNA moiety at its 5'-end: (1) the nascent DNA was resistant to exonucleolytic degradation by spleen phosphodiesterase unless first hydrolyzed by strong alkali or ribonuclease; (2) the 5'-termini of nascent DNA could not be phosphorylated by polynucleotide kinase unless first treated with alkaline phosphatase or subjected to hydrolysis by strong alkali or ribonuclease; (3) alkaline hydrolysis of nascent DNA labeled with 32P at the 5'-end released unlabeled DNA with a free 5'-terminus and 32P-labeled ribonucleoside 3',5'-bisphosphates; (4) ribonuclease degradation of similarly labeled material produced an unlabeled DNA-containing polynucleotide fraction and 32P-labeled ribo-oligonucleotides; (5) chromatography on dihydroxyboryl cellulose showed that the RNA moiety lacked a 3'-terminal cis-diol grouping (even after treatment with alkaline phosphatase) unless first subjected to the 3'-exonucleolytic action of bacteriophage T4 DNA polymerase. The sequence of the ribonucleotide chains was elucidated by end-group labeling with polynucleotide kinase and digestion with various ribonucleases. The ribonucleotide moiety was primarily three and four residues in length with the predominant sequence (pp)pApG(pC)1-2pDNA. The possibility that it represents a primer for discontinuous DNA synthesis is discussed.
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PMID:Analysis of the 5'-termini of nascent DNA chains synthesized in permeable cells of Bacillus subtilis. 618 36

Column chromatographic purification and sensitivity towards enzymatic treatments of dialyzable transfer factor (TFd), the immunologically specific component of dialyzable leukocyte extract (DLE), have previously been used in its biochemical characterisation. In the present work we studied the effect of enzymes and the Sephadex G-10 chromatographic separation of the components of DLE augmenting delayed-type hypersensitivity. Skin reactivities to streptokinase-streptodornase (SK-SD) and tuberculin PPD were significantly augmented by injecting DLE into antigen-primed guinea pigs. The augmentation caused by DLE treatment correlated to the pre-existing level of immunity in the recipients. Most of the augmentory activity resided in 2 adjacent fractions, eluting early from a Sephadex G-10 column. This augmentation was destroyed by alkaline hydrolysis, by treatment with pronase, proteinase K, ribonuclease, and nuclease P1, but not by alkaline phosphatase or phosphodiesterase II. The observed sensitivities towards these enzymes, except that for ribonuclease, were closely similar to those described for the specific TFd component of DLE. These results are compatible with the idea that either the nonspecific augmenting and the specific TFd molecules are principally similar, or that the TFd molecules, in addition to their capacity to transfer specific immunity, also have an augmenting effect, which needs in its manifestation a sub-threshold dose of immunogen.
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PMID:Augmentation of delayed-type hypersensitivity in antigen-primed guinea pigs by human dialyzable leukocyte extract. Chromatographic and enzymatic characterization of the active principle. 676 49

We describe a method for obtaining radioactive fingerprints from nonradioactive ribonucleic acid. Fragments derived by T1 ribonuclease digestion of RNA are dephosphorylated with bacterial alkaline phosphatase. When these fragments are used as primers for the reaction of primer dependent polynucleotide phosphorylase with [alpha-(32)P]GDP in the presence of T1 ribonuclease the 3'-hydroxyl group of each fragment becomes phosphorylated. The degree of phosphorylation is reasonably uniform. The method has been applied to T1 ribonuclease digests of Escherichia coli tRNA(Met) (f); the oligonucleotides were further analyzed by spleen phosphodiesterase digestion. In a similar manner fingerprints of pancreatic ribonuclease digests of RNA can be obtained, when [alpha-(32)P]UDP, polynucleotide phosphorylase and pancreatic ribonuclease are used.
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PMID:Fingerprinting nonradioactive ribonucleic acid with the aid of polynucleotide phosphorylase. 1079 69

The multifunctional ribonuclease RNase E and the 3'-exonuclease polynucleotide phosphorylase (PNPase) are major components of an Escherichia coli ribonucleolytic "machine" that has been termed the RNA degradosome. Previous work has shown that poly(A) additions to the 3' ends of RNA substrates affect RNA degradation by both of these enzymes. To better understand the mechanism(s) by which poly(A) tails can modulate ribonuclease action, we used selective binding in 1 m salt to identify E. coli proteins that interact at high affinity with poly(A) tracts. We report here that CspE, a member of a family of RNA-binding "cold shock" proteins, and S1, an essential component of the 30 S ribosomal subunit, are poly(A)-binding proteins that interact functionally and physically, respectively, with degradosome ribonucleases. We show that purified CspE impedes poly(A)-mediated 3' to 5' exonucleolytic decay by PNPase by interfering with its digestion through the poly(A) tail and also inhibits both internal cleavage and poly(A) tail removal by RNase E. The ribosomal protein S1, which is known to interact with sequences at the 5' ends of mRNA molecules during the initiation of translation, can bind to both RNase E and PNPase, but in contrast to CspE, did not affect the ribonucleolytic actions of these enzymes. Our findings raise the prospect that E. coli proteins that bind to poly(A) tails may link the functions of degradosomes and ribosomes.
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PMID:Escherichia coli poly(A)-binding proteins that interact with components of degradosomes or impede RNA decay mediated by polynucleotide phosphorylase and RNase E. 1139 Mar 93

Poly(A)-specific ribonuclease (PARN) is the only mammalian exoribonuclease characterized thus far with high specificity for degrading the mRNA poly(A) tail. PARN belongs to the RNase D family of nucleases, a family characterized by the presence of four conserved acidic amino acid residues. Here, we show by site-directed mutagenesis that these residues of human PARN, i.e. Asp(28), Glu(30), Asp(292), and Asp(382), are essential for catalysis but are not required for stabilization of the PARN x RNA substrate complex. We have used iron(II)-induced hydroxyl radical cleavage to map Fe(2+) binding sites in PARN. Two Fe(2+) binding sites were identified, and three of the conserved acidic amino acid residues were important for Fe(2+) binding at these sites. Furthermore, we show that the apparent dissociation constant ((app)K(d)) values for Fe(2+) binding at both sites were affected in PARN polypeptides in which the conserved acidic amino acid residues were substituted to alanine. This suggests that these residues coordinate divalent metal ions. We conclude that the four conserved acidic amino acids are essential residues of the PARN active site and that the active site of PARN functionally and structurally resembles the active site for 3'-exonuclease domain of Escherichia coli DNA polymerase I.
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PMID:Identification of the active site of poly(A)-specific ribonuclease by site-directed mutagenesis and Fe(2+)-mediated cleavage. 1174 7

The rapid degradation of ribonucleic acids (RNA) by ubiquitous ribonucleases limits the efficacy of new therapies based on RNA molecules. Therefore, our aim was to characterize the natural ribonuclease activities on the skin and in blood plasma i.e. at sites where many drugs in development are applied. On the skin surfaces of Homo sapiens and Mus musculus we observed dominant pyrimidine-specific ribonuclease activity. This activity is not prevented by a cap structure at the 5'-end of messenger RNA (mRNA) and is not primarily of a 5'- or 3'-exonuclease type. Moreover, the ribonuclease activity on the skin or in blood plasma is not inhibited by chemical modifications introduced at the 2'OH group of cytidine or uridine residues. It is, however, inhibited by the ribonuclease inhibitor RNasin although not by the ribonuclease inhibitor SUPERase* In. The application of our findings in the field of medical science may result in an improved efficiency of RNA-based therapies that are currently in development.
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PMID:Characterization of the ribonuclease activity on the skin surface. 1673 88


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