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)

The region of the ovalbumin messenger ribonucleic acid (mRNAov) molecule bound to the 40S ribosomal subunit and its associated initiation factors in the wheat germ cell-free translation system were isolated and characterized. Two mRNAov fragments, 87 and 92 nucleotides in length, were protected from T1 ribonuclease digestion by binding of guanosine 5',beta,gamma-methylenetriphosphate and were shown by hybridization and fingerprint mapping to be derived from the 5' end of mRNAov. Both these mRNAov fragments were of sufficient length to contain both the cap structure and the AUG initiation codon. Four T1-resistant oligonucleotides, prepared by direct digestion of mRNAov with T1 ribonuclease were also found to bind to the wheat germ 40S ribosomal subunit. Nucleotide sequence analysis of these oligonucleotides revealed (1) that they were not a subset of the ribosome binding fragments described above, (2) that they were derived from within the mRNAov molecule (one from within the coding region and three from the noncoding region at the 3' end of the mRNAov molecule), and (3) that three of the four mRNAov nucleotides contained 3'-terminal AUG trinucleotides. These data suggested that features of the mRNAov molecule in addition to the nucleotide sequence might be important in specifying the correct ribosome binding site for the initiation of protein synthesis. The amount of mRNAov bound to the wheat germ 40S ribosomal subunit in a preinitiation complex was found to vary inversely with the potassium ion concentration. Lowering the potassium concentration to levels suboptimal for translation also resulted in the protection of larger fragments of the mRNAov molecule derived from the same 5'-end region as the ribosome binding fragments described above. The ability of the cap analogue 7-methylguanosine 5'-phosphate (m7G5'p) to reduce the amount of mRNAov bound to the wheat germ 40S ribosomal subunit was found to depend directly on thepotassium concentration. Interestingly, the effects of potassium on the amount of mRNAov bound in a preinitiation complex and the inhibition of this binding by m7G5'p could be observed by changing the potassium concentration after binding had occurred. These data suggested that the interaction between the wheat germ 40S ribosomal subunit and mRNAov was very sensitive to the ionic environment.
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PMID:Ribosome binding site analysis of ovalbumin messenger ribonucleic acid. 11 32

Infectious bursal disease (IBD) virus was purified from the bursae of infected chickens. Two morphologically indistinguishable populations of virus particles were separated in sucrose gradients and possessed sedimentation coefficients of 295S and 460S. Both populations contained RNA and had identical polypeptide compositions. IBD virus banded at a density of 1.31 g/ml in CsCl and at 1.24 g/ml in sodium potassium tartrate. IBD virus contained two RNA segments with mol. wts. of 2.4X10(6) and 2.2X10(6) as estimated by polyacrylamide-agarose gel electrophoresis, but sedimented in sucrose gradients at 15S. Virus RNA was resistant to 0.1 micrograms/ml ribonuclease treatment under conditions in which ribosomal RNA was completely hydrolysed, but was sensitive to 1.0 and 10 micrograms/ml treatments. These results suggest that the RNA consists of either double-stranded or highly ordered single-stranded molecules. IBD virus contained seven polypeptides with mol. wts. in the range 97,000 to 24,000. Two polypeptides were absent in empty particles of IBD virus. IBD and infectious pancreatic necrosis (IPN) viruses were morphologically indistinguishable. IPN virus possessed a sedimentation coefficient of 440S and banded at a density of 1.32 g/ml in CsCl. In addition the electrophoretic mobilities of IBD and IPN virus RNAs were almost identical. Polyacrylamide slab gel electrophoresis showed that while the number and size of the polypeptides were different for each virus there were similarities in the overall pattern.
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PMID:Biochemical studies with infectious bursal disease virus: comparison of some of its properties with infectious pancreatic necrosis virus. 22 37

Preparations of radioactive lysosomes were obtained from mouse kidney after injection of radioactive iodine-labeled bovine ribonuclease. Stability of these lysosomes in various media was estimated from measurements of proteolytic activity towards the ribonuclease, and of ribonuclease retention in particles. The lysosomes were stable at 37 degrees C in isotonic, sucrose-free solutions of KCl, NaCl, and potassium acetate, and in mixtures of these with MgCl2, showing that these salts are relatively impermeant through the lysosomal membranes. The membranes were less permeable to Na+ than to K+. Both KCl and NaCl exerted their optimal protective effects over a broad concentration range above 0.125 M in 0.025 M acetate buffer. Mg2+ enhanced the protective effect of both K4 and Na+; the osmotic effect of 0.075 M NaC1-0.05 M MgCl2 was indistinguishable during the entire course of ribonuclease digestion from that of isotonic sucrose. Osmotic protection by KC1-MgC12 was demonstrated over the H range5.5-7.0. A marked alteration in membrane properties occurs at lower temperatures in 0.11 M KC1-0.01 M MgCl2 such that, at 0 degrees C, K+ permeability is much higher than at 37 degrees C, as shown by a several-fold decrease in stability at the lower temperature.
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PMID:A thermally induced alteration in lysosome membranes: salt permeability at 0 and 37 degrees C. 23 78

There is a deficiency of initiation in protein-synthesizing systems prepared from mammalian epidermis. These systems do not respond to inhibitors of initiation although they remain sensitive to elongation inhibitors and exogenous ribonuclease. In spite of this deficiency of initiation, active protein factors which support initiation reactions are present in the potassium chloride extract of mammalian epidermal ribosomes. A factor corresponding to the reticulocyte factor IF-MP has been isolated. An inhibitor of initiation is also present in the epidermal KCl wash.
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PMID:Mammalian epidermal protein synthesis: initiation factors. 95 Apr 88

The neurotoxic gamma-diketone, 2,5-hexanedione, reacts with axonal protein amine residues to form 2,5-dimethylpyrrole adducts. Current evidence implicates this reaction as the potentially critical step in gamma-diketone neurotoxicity, although it is unclear whether pyrrole formation per se is sufficient to induce neuropathy or whether secondary autoxidative reactions are also required. The present in vitro study examines aspects of pyrrole formation and the secondary phenomena of chromophore development and covalent protein crosslinking in 2,5-hexanedione-treated protein. p-Dimethylaminobenzaldehyde (DMAB)-detectable pyrrole concentrations decreased linearly with time when pyrrolylated bovine serum albumin (pyrrole-BSA) was incubated under air, but remained unchanged following N2 incubation. The air-induced decrease was accompanied by the appearance of chromophores and crosslinked protein. Covalent crosslinking of pyrrole-BSA was pH-dependent, with relatively increased intermolecular bridging at pH 7.4 as compared to pH 9.5. Chromophore formation and the loss in DMAB-detectable pyrrole were also accelerated at the lower pH. Autoxidative parameters were inhibited in the presence of a free radical scavenger (ascorbic acid) but induced by free radical initiators (potassium persulfate and 2,2'-azobis[2-amidinopropane hydrochloride]). In vitro incubation followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of combinations of bovine serum albumin, ribonuclease, pyrrole-BSA, and pyrrolylated ribonuclease revealed that the intermolecular crosslinking pathway was mediated by pyrrole-pyrrole bridging. These findings demonstrate that the secondary autoxidative phenomena following pyrrole adduct formation in gamma-diketone-treated protein proceed via pH-dependent, free radical-mediated mechanisms. If similar mechanisms are present in vivo, the results also suggest that intermolecular covalent crosslinking of pyrrolylated axonal protein may be less widespread and more specific than previously thought.
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PMID:Mechanisms of in vitro pyrrole adduct autoxidation in 2,5-hexanedione-treated protein. 377 83

A rapid method for the extraction and purification of DNA from human leukocytes was developed. Crude nucleic acids were obtained by sodium dodecylsulfate (SDS) lysis and potassium acetate precipitation of other cellular material, and the DNA was purified by ribonuclease digestion, diethylaminoethyl (DEAE) cellulose chromatography and ethanol precipitation. DNA obtained by this method is biologically active as reflected by its ability to act as substrate for various nucleases and T4 DNA ligase. The yield was sufficiently high that DNA from less than 1 ml of blood could be used for a number of reactions.
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PMID:A rapid method for the extraction and purification of DNA from human leukocytes. 399 5

1. Treatment of washed rat liver microsomes in a medium containing 0.12m-sucrose, 12.5mm-potassium chloride, 2.5mm-magnesium chloride and 25mm-tris-hydrochloric acid buffer, pH7.6, with 2m-lithium chloride at 5 degrees for 16hr. leads to the formation of membranes free of ribosomes and ribosomal subunits. 2. Confirmation of the absence of ribosomes from lithium chloride-prepared membranes was obtained by treatment of the membranes with sodium deoxycholate, followed by sucrose-density-gradient centrifugation, which showed the complete absence of ribosomes. 3. Treatment of membranes with phenol, followed by sucrose-density-gradient analysis of the isolated RNA, showed the presence of a small amount of 4s material. Repetition of the phenol extraction procedure in the presence of liver cell sap as a ribonuclease inhibitor again showed the presence of only 4s material. The 4s RNA was shown to be transfer RNA by the fact that it had the same capacity for accepting (14)C-labelled amino acids as isolated transfer RNA from rat liver pH5 enzyme. 4. Analysis showed that microsomes and membranes possessed similar glucose 6-phosphatase, NADH-2,6-dichlorophenol-indophenol reductase, NADH-neo-tetrazolium reductase, NADH-cytochrome c reductase and ribonuclease activities. 5. (3)H-labelled ribosomal RNA binds to membranes. However, isolation of the bound RNA by the phenol extraction procedure, followed by sucrose-density-gradient analysis, shows the RNA to be degraded to 7s material. Very little breakdown of (3)H-labelled ribosomal RNA bound to membranes occurs if the binding and isolation are carried out in the presence of liver cell sap.
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PMID:Preparation of ribosome-free membranes from rat liver microsomes by means of lithium chloride. 431 14

After the attachment of radioactive coxsackievirus B3 to HeLa cells at 0 C and subsequent incubation at 37 C, 50 to 80% of attached virus radioactivity was eluted from the cells within 1 hr. Eluted virus had a buoyant density of 1.21 in a potassium tartrate gradient, sedimented more slowly than native virus in sucrose gradients, was resistant to ribonuclease, was unstable in CsCl centrifugation, and did not reattach to uninfected cells. Electrophoretic studies of sodium dodecyl sulfate-disrupted B3 virus in sodium dodecyl sulfate-polyacrylamide gels revealed four radioactive virus polypeptides (VP 1 to 4), of which the three largest migrated slightly faster than their poliovirus T1 counterparts. In contrast, electrophoretic analysis of eluted virus, after banding in a tartrate gradient or pelleting by centrifugation, showed the absence of the fastest migrating polypeptide, VP 4. VP 4 was recovered in the supernatant fluid when the eluted virions were removed by high-speed centrifugation. The results indicate that VP 4 is located at the surface of the native virion, and its dissociation from the capsid may represent the first specific alteration of the virion after virus-receptor interaction at the cell surface.
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PMID:Specific alterations of coxsackievirus B3 eluted from HeLa cells. 433 54

1. A simple method for the preparation of ribonuclease-free ribosomal RNA is described in which ribonuclease-deficient bacteria are treated with acetone and the RNA is extracted with phenol and purified by precipitating it with potassium acetate. The treatment with acetone appears to render the cell wall permeable to RNA but not to DNA during the extraction with phenol. The method thus avoids the need to disrupt the bacteria and greatly simplifies the subsequent purification. 2. The method has been used successfully with ribonuclease-deficient strains of Escherichia coli, Pseudomonas fluorescens and Staphylococcus epidermidis. The recovered purified RNA accounts for about 70% of the total ribosomal RNA and shows the normal sedimentation pattern of the 16s and 23s components in the analytical centrifuge.
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PMID:The preparation of ribosomal ribonucleic acid from whole bacteria. 486 33

During inhibition of the growth of Escherichia coli by cobalt chloride protein synthesis was decreased more than the synthesis of RNA. Three species of particle accumulated during the incubation. These had sedimentation coefficients of about 44s, 33s and 23s in tris buffer containing 10 mm-magnesium acetate and 100 mm-potassium chloride, but their sedimentation properties were susceptible to changes in buffer composition. The particles contained RNA but were more readily degraded by ribonuclease than were the ribosomes. RNA isolated from the particles differed slightly in sedimentation properties from the major species of ribosomal RNA. The particles are likely to be closely related to ribosome precursors that have been detected in other circumstances. Changes in the polyribosome fraction during inhibition by cobalt chloride, nickel chloride and chloramphenicol provided further evidence that inhibition by Co(2+) involves specific effects on the protein-synthesizing machinery.
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PMID:Inhibition of bacterial growth by metal salts. The accumulation of ribonucleic acid during inhibition of Escherichia coli by cobalt chloride. 490 80


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