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)

Nerve growth factor (NGF) receptor binding in membrane fractions of rabbit superior cervical ganglia has been measured after treatment with a variety of enzymes, protein-modifying reagents, and ions. Receptor binding is degraded by low concentrations of trypsin but is much less sensitive to alpha-chymotrypsin. Low concentrations of phospholipase A from Vipera russelli decrease NGF receptor binding by lowering the number of binding sites, while phospholipase A preparations from Crotalus terrificus terrificus and bee venom do not affect binding. Phospholipase C and D, neuraminidase, DNase, and RNase have minimal effects on receptor binding. NGF receptor binding appears to be absolutely dependent upon calcium ion. Removal of calcium from the incubation medium greatly reduces binding as does treatment with EDTA. Maximal receptor binding occurs at 5 mM calcium. Magnesium and sodium are unable to substitute for calcium. Receptor binding is greatly reduced by treating membranes with 2-hydroxy-5-nitrobenzyl bromide, 2-methoxy-5-nitrobenzyl bromide, diazonium tetrazole, and tetranitromethane. NGF receptor sites can be protected from 2-hydroxy-5-nitrobenzyl bromide by incubation with NGF.
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PMID:Nerve growth factor receptor binding. Influence of enzymes, ions, and protein reagents. 80 4

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

A fraction containing membrane-bound tobacco mosaic virus RNA replicase was isolated form tobacco mosaic virus-infected tobacco callus cultures. The replicase activity reached a maximum 60 h after inoculation and then declined. The enzyme activity was insensitive to actinomycin D and DNase. The corresponding fraction from healthy callus contained essentially no activity. The viral RNA synthesis in vitro proceeded linearly for 30 min and required the four nucleotide triphosphates and Mg2+ ions. Mn2+ was a poor substitute for Mg2+. During RNA synthesis the product was at least 70% resistant to RNase in 2X SSC (0.15 M NaCl plus 0.015 M sodium citrate), but completely digested by RNase in 0.1X SSC. Analysis of the product by polns) that appeared to be replicative form and a partially RNase-resistant structure similar to replicative intermediate form. Washing the membrane-bound replicase with Mg2+-deficient buffer solubilized enzyme. The solubulized enzyme was further purified by DEAE-Sephadex column chromatography. The DEAE-purified enzyme was nearly completely dependent upon tobacco mosaic virus RNA for activity. Analysis of the product on a sucrose gradient revealed a double-stranded RNA with sedimentation of 16S and smaller heterogeneous RNase-sensitive products.
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PMID:In vitro replication of tobacco mosaic virus RNA in tobacco callus cultures: solubilization of membrane-bound replicase and partial purification. 83 35

The dependence of activation of latent RNAse of RNP particles isolated from rat skeletal muscles, on the concentration of K+ and Mg2+ in the incubation medium and on temperature was studied. During a short-term exposure (20 min 18 degrees) of RNP particles in the buffers containing K+ at concentrations varying from 0.05 M to 0.25 M and Mg2+ at concentrations from 0.001 M to 0.01 M no effect of endogenous ribonuclease was observed. It was shown that a significant activation of latent RNAse occurs during the incubation at room temperature in 24 hours provided that the incubation medium contains Mg2+ at concentrations not higher that 0.004 M. In the presence of 0.004 M Mg2+ degradation of polysomal mRNA and partial degradation of 18 S--rRNA takes place. At Mg2+ concentration as low as 0.001 M not only mRNA but also both rRNAs are accessible to the action of activated ribonuclease. 20 min heating of RNP particles up to 55 degrees C causes insignificant degradation of the polysomes and 18 S--rRNA. The increase in temperature by 5 degrees c results in the activation of latent RNAse followed by an almost complete degradation of mRNA and rRNA. The relationship between the integrity of the ribosomal structure and activation of latent ribonuclease is discussed.
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PMID:[Activation of latent RNAse activity of RNP particles from rat skeletal muscles]. 85 24

A procedure is described for the isolation of polyribosomes from crude tissue homogenates of germinated pea seeds using Mg2+ precipitation in the presence of the ribonuclease inhibitor heparin. Collection of the polyribosomal pellet does not require the use of an ultracentrifuge. The method has a potentially wide application for polyribosome and messenger ribonucleoprotein isolation and might also be useful where conventional techniques have failed.
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PMID:The isolation of polyribosomes from plant material using magnesium precipitation in the presence of heparin. 89 May 82

A quantitative assay was developed to permit estimation of the relative amounts of albumin-synthesizing polyribosomes in rat liver. The polyribosomes synthesizing albumin were identified by their capacity to bind anti-RSA Fab' radiolabeled with 125I. The anti-RSA Fab'-binding sites occur on the nascent peptide chains attached to liver polyribosomes. These binding sites can be saturated by preincubation of the polyribosomes with large quantities of unlabeled anti-RSA Fab'. The iodinated antibody did not react with polyribosomes isolated from a tissue which does not synthesize rat serum albumin. Pretreatment of hepatic polyribosomes with bovine pancreatic ribonuclease resulted in a 42% enhancement of binding of anti-RSA Fab'. Pretreatment of these polyribosomes with detergents or various levels of Mg2+ did not significantly affect the specific binding of the iodinated antibody. Anti-RSA Fab' associated preferentially with membrane-bound polyribosomes when compared with free polyribosomes following their isolation from animals maintained either on a 90% or a 0% protein diet fed ad libitum. Binding of anti-RSA Fab' to each A260 unit of membrane-bound polyribosomes is from 2.4 to 27 times greater than to each A260 unit of free polyribosomes. However, each A260 unit of free polyribosomes was found to associate with 1.8 times more anti-RSA Fab' when compared with the "loosely bound" subclass of membrane-bound polyribosomes. Each A260 unit of the "tightly bound" subclass of membrane-bound polyribosomes reacted with 4.3 times as much antibody as compared with free polyribosomes. Polyribosomes isolated from the livers of rats sacrificed 6 h after treatment with actinomycin D showed a 42% reduction in their capacity to bind anti-RSA Fab'. Polyribosomes from rats sacrificed 2 h after treatment with actinomycin D showed no reduction in binding capacity. Free polyribosomes from three Morris hepatomas were capable of binding anti-RSA Fab' whereas the antibody would not associate with the membrane-bound polyribosomes of the same hepatomas. Thus the binding of 125I-labeled Fab' antibody molecules to polyribosomes is a useful technique for the subcellular localization of polyribosomes synthesizing specific proteins and for the estimation of the relative proportions of such polyribosomes.
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PMID:The effect of various treatments in vitro and in vivo on the binding of 125I-labeled anti-rat serum albumin Fab' to rat tissue polyribosomes. 95 77

Polycations, including ribonuclease A, ribonuclease S protein and peptide, spermine, spermidine, and polylysines, enhance unstimulated and stimulated adenylate cyclase activity of beef thyroid membranes at low concentrations and inhibit these activities at high concentrations. Peak polylysine stimulation occurs with degrees of polymerization of 6 to 14, and for large polymers a potency limit for this maximum is reached at 4 X 10(-5) M expressed as lysine residues. Both enhancement and inhibition appear to be due to charge-charge interactions and are abolished by KC1. Polyanions are inhibitory only. The biphasic effect of polycations is seen on basal cyclase activity, occurs with prostaglandin E1- and 5'-guanylyl-imidodiphosphate-stimulated cyclase, but is most striking with thyrotropin. There is little enhancement of F--activated cyclase. The enhancement is not sensitive to changes in pH, Mg2+, or regenerating system and does not correlate with the stability constants between polycations and ATP. We suggest that the polycation effect is a general, electrostatic effect on membrane conformation and is not restricted to a particular receptor domain.
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PMID:Charge effects in the activation of adenylate cyclase. 115 87

The strains of beta-hemolytic streptococci capable of producing streptolysin S, Su and Blackmore, were found to be useful in acquiring CIH (colistin-induced hemolysin), while C203U strain, which produces only streptolysin O, was ineffective in this respect. In these experimental series, much amounts of coccal cells from exponential phase of culture were necessary for obtaining good results and for its reproducibility. Further experiments showed that an oligoribonucleotide, rich in guanylic residu, separated by DEAE-cellulose column chromatography could be favourably compared with RNase-core in production of CIH in the medium. Yield of this hemolysin was fully dependent upon the concentration of K+ (100 mM), Mg2+ (10 mM) ions and maltose (5 mM) contained in the reaction medium, respectively. When one of three components was omitted, CIH was not obtained, even though colistin and oligoribonucleotide were present. Additionally, crude preparation of CIH was fractionated on DEAE-cellulose column, resulting in isolation of two peaks (F-I and F-II) with hemolytic activity. Considering the response of two hemolytic fractions to various inhibitors and activators, F-II is likely to correspond to streptolysin S, while F-I may, at least, be a segment differed from the streptolysin, S and O.
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PMID:Isolation and properties of a streptococcal hemolysin formed in the presence of colistin. 123 62

Earlier work has shown that the inhibition by pactamycin (PM) of polypeptide chain initiation in reticulocyte extracts is associated with (1) a defect in the joining of the 60S subunit to the smaller initiation complex to form an 80S complex ("joining reaction") (Kappen, L. S., Suzuki, H., and Goldberg, I. H. (1973), Proc. Natl. Acad. Sci. U.S.A. 70, 22) and (2) a block after the synthesis of the initial dipeptide (Kappen, L. S., and Goldberg, I. H. (1973), Biochem. Biophys. Res. Commun. 54, 1083). The relative contributions of these two effects to the action of PM and their relationship to one another were evaluated in a system employing sparsomycin that permits both initiation at a certain number of initiation sites and limited oligopeptide formation without termination and release. The degree to which PM blocks the "joining reaction" and leads to the accumulation of 48S initiation complexes that either remain free or are bound to polysomes without the corresponding 60S subunit ("half-mers") was estimated by treatment of polysomes with RNase. Met-tRNAfMet binding factors are required to stabilize the RNase-generated 48S complexes. Under conditions where the initiation factor required for the "joining reaction" functions catalytically, presumably by cycling on and off initiation complexes, PM usually inhibits 80S complex formation 50-70%. Where "joining" is not limiting (presence of at least stoichiometric amounts of joining factor or high Mg2+ concentration) PM leads to the maximal accumulation of the initial dipeptide, Met-Val, in the P-site on the ribosome, indicating a block in a subsequent step in elongation. Binding studies with [3H]PM and the inability of PM to inhibit elongation of preformed Met-Val indicate that PM must interact with the ribosomes at an early stage of initiation. Taken together these data are compatible with the suggestion that PM does not interfere with the ribosomal "joining reaction" per se, but prevents the release and reuse of the joining factor, and in so doing blocks a step in elongation after formation of the initial dipeptide and its translocation to the P-site on the ribosome.
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PMID:Analysis of the two steps in polypeptide chain initiation inhibited by pactamycin. 124 35

An endo-exonuclease has been purified from cultured monkey (CV-1) cells. The enzyme which was purified to near homogeneity to be a 65 kDa monomeric protein. The single-strand DNase activity is endonucleolytic and nonprocessive, whereas the double-strand DNase activity is exonucleolytic and processive. The enzyme was also found to have RNase activity using poly-rA as substrate. The pH optimum for ss-DNase is 8 and for ds-DNase it is 7.5. Both DNase activities require a divalent metal ion (Mg2+, Mn2+, Ca2+, Zn2+) for activity and exhibit the same kinetics of heat inactivation. The purified protein binds to and cleaves a synthetic Holliday junction substrate. The overall enzymatic characteristics of the mammalian protein are very similar to the putative recombination endo-exonucleases purified from Neurospora crassa, Aspergillus nidulans and Saccharomyces cerevisiae.
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PMID:Purification and characterization of a mammalian endo-exonuclease. 132 80


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