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)

The early stages of thermal unfolding of the tertiary structure of yeast tRNAPhe have been followed, in the presence and absence of Mg2+, by measuring changes in the chemical accessibility of the bases uracil and guanine. The reagent used in these studies is 1-cyclohexyl 3-[2-morpholino(4)-ethyl]carbodiimide methotosylate. 32P-labelled tRNA was used so that the points of modification could be examined with ribonuclease digestion and established fingerprinting techniques. Two regions of protection of Mg2+ have been found. One is within the oligonucleotide U8-A-m2G10 and the other is in the vicinity of residue U-59. The tertiary interactions and the D stem are the most readily melted parts of the teritary structure. In the absence of Mg2+ the region of U-59 is the first part of the tertiary structure to become accessible to the reagent. This is closely followed by the opening up of the 'wobble' G-U base pair in the aminoacyl stem. Most of the triple interactions in the augmented D helix are also disrupted early in the melting. The region of intricate interactions between the invariant G-G part of the D loop and the T-psi-C-G loop contains the most stable set of tertitary structure interactions.
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PMID:Initial stages of the thermal unfolding of yeast phenylalanine transfer RNA as studied by chemical modification: the effect of magnesium. 41 74

Studies using isogenic transductant strains mlpA+ and mlpA as well as reversion analysis suggested that the physiological consequences of a structural gene mutation in murein lipoprotein include (i) increased sensitivity toward chelating agents ethylenediaminetetraacetic acid and ethyleneglycol-bis (beta-aminoethyl ether)-N,N-tetraacetic acid, (ii) leakage of periplasmic enzyme ribonuclease, (iii) weakened association between the outer membrane and the rigid layer accentuated by Mg2+ starvation, resulting in the formation of outer membrane blebs, and (iv) decreased growth rate in media of low ionic strength or low osmolarity. It is suggested that the bound form of lipoprotein plays an important role in the maintenance of the structural integrity of the outer membrane of the Escherichia coli cell envelope. Other outer membrane components may also contribute to the anchorage of outer membrane to the rigid layer, probably through ionic interactions with divalent cations. Using the phenotype of ribonuclease leakage as an unselected marker in a three-factor cross with P1 transduction, we were able to establish the gene order of man mlpA aroD pps on the E. coli chromosome.
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PMID:Physiological characterization of an Escherichia coli mutant altered in the structure of murein lipoprotein. 41 67

Though DNase does not contain any cysteine residues, incubation of the enzyme with 2-nitro-5-thiocyanobenzoic acid in the presence of Ca2+ at pH values above 7.5 results in an irreversible inactivation of the enzyme. The inactivation also occurs when Ca2+ is replaced by Mg2+, but not in their absence. Amino acid analyses after acid hydrolyses of the completely inactivated ant the native enzymes show no significant differences in composition, including tryptophan and half-cystine residues. However, sodium dodecyl sulfate gel electrophoresis indicates enzyme cleavage by the treatment with 2-nitro-5-thiocyanobenzoic acid. This reagent does not inactivate chymotrypsin and lysozyme, and under conditions where bovine DNase is inactivated, does not inactivate other nucleases such as ribonuclease, snake venom phosphodiesterase, and spleen acid DNase. However, it inactivates malt DNase and can, therefore, be considered a specific inhibitor of DNase I. The inactivation kinetics is pseudo-first order, resembling Michaelis-Menten, with an affinity constant of 16.7 mM. It is the cyano group, not the thionitrobenzoic acid of 2-nitro-5-thiocyanobenzoic acid that reacts to form cyano-DNase.
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PMID:Inactivation of bovine pancreatic DNase by 2-nitro-5-thiocyanobenzoic acid. I. A novel inhibitor for DNase I. 48 54

The Mg2+-precipitable polysomes in experimental granulation tissue increase up to three weeks and decrease slowly thereafter. Polysomes from young granulation tissue are, on a weight basis, more active in cell-free protein synthesis than polysomes from old granulation tissue. RNase activity is highest in polysomes from 1-week tissue. The polysomes contain both acid and alkaline RNase, but the alkaline RNase is the latent form, manifested by the addition of p-chloromercuribenzoate (pCMB). The high RNase activity of granulation tissue renders the analysis of polysomal patterns and functions of the polysomes difficult. In the post-polysomal supernatant of granulation tissue the RNase activity is highest in 2-4 week old tissue; it is maximal at pH 7-8 and only slightly influenced by pCMB.
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PMID:Ribonuclease activities in developing experimental granulation tissue with reference to polysomes. 50 66

Myosin purified from Dictyostelium amoebae has approximately 10% by weight of RNA associated with it, unless specific steps (DEAE cellulose chromatography or RNase digestion) are taken to remove it. This RNA has significant effects on the structural states formed by the myosin at low ionic strength in the presence of Mg2+. Rapid precipitation of RNA-free myosin by dilution generates bipolar thick filaments (540 nm long, 33 nm thick), often with a bare zone and a 15-nm transverse repeat. Rapid precipitation of myosin with copurified RNA yields linear aggregates of bipolar filaments, showing some lateral association. Slow precipitation of RNA-free myosin by dialysis yields very long filaments or ribbons (greater than 5 micrometer, 30--60 nm wide) in which the myosin may be packed diagonally across the filament, similar to the "side-polar" aggregates formed by other nonmuscle myosins and by smooth muscle myosin (Craig R, Megerman J: J Cell Biol 75:990, 1977; Hinssen H, D'Haese J, Small JV, Sobieszek A: J Ultrastruct Res 64:282, 1978). Slow precipitation of myosin with copurified RNA generates linear filaments with repeat intervals of 290 and 650 nm. Other polyanions were tested for their effects on myosin aggregation. Total RNA and ribosomal RNA from Dictyostelium, when added to RNA-free myosin, also induced the extensive linear aggregation seen with the copurified RNA/myosin complex, although higher concentrations of RNA were required to obtain quantitatively the same effect. DNA and heparin were also effective inducers of linear aggregation, whereas homopolymers of nucleotides and of acidic or basic amino acids were poorly effective.
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PMID:Structural states of dictyostelium myosin. 54 31

Atypical eukaryotic RNA polymerase activity was demonstrated in nuclei of Crypthecodinium cohnii, a eukaryote devoid of histones. Nuclei were isolated from growing cultures of this dinoflagellate and assayed for endogenous RNA polymerase (EC 2.7.7.6) activity. There was a biphasic response to Mg2+ with optima at approximately 0.01 and 0.02 M MgCl2, but in contrast to other eukaryotic RNA polymerases, this enzyme activity was inhibited by low MnCl2 concentrations. In the presence of 0.01 M MgCL2 the optimum (NH4)2SO4 concentration was 0.025 M, a concentration at which the nuclei were lysed. Incorporation of [3H]UMP into RNA was inhibited by actinomycin D and dependent on the presence of undergraded DNA, and the reaction product was sensitive to ribonuclease and KOH digestion. Omission of one or more ribonucleoside triphosphates greatly reduced the incorporation. Only a slight enhancement of RNA polymerase activity resulted from the addition of various amounts of native and denatured calf thymus DNA. Spermine caused a marked inhibition while spermidine had little effect on RNA synthesis in the nuclei. Under the optimum conditions described in the present paper the nuclei incorporated approximately 3 pmoles of [3H]UMP/microgram DNA at 25 C for 15 min, and approximately 80% of this activity was inhibited by the eukaryotic RNA polymerase II inhibitor, alpha-amanitin (20 micrograms/ml). A unique situation therefore exists in C. cohnii nuclei, in which absence of histones (a prokaryotic trait) is combined with alpha-amanitin-sensitive RNA polymerase activity (a eukaryotic trait).
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PMID:RNA synthesis in isolated nuclei of the dinoflagellate Crypthecodinium cohnii. 57 93

Dormant gastrulae and developing embryos of the brine shrimp Artemia salina contain very low levels of nuclease activity. During early larval development, there is an induction of ribonuclease which has been partially purified and characterized. The enzyme catalyzes an endonucleolytic cleavage of RNA and has no detectable activity on native or denatured DNA. Among a series of synthetic polynucleotides, poly(U) is hydrolyzed with the highest efficiency and poly(G) is not cleaved by the enzyme. The activity on poly(U) is 100 times higher than on RNA. The enzyme requires Mg2+ or Mn2+ and in inactivated by treatment with chelating agent. The inactive preparations can be reactivated by Ca2+ and Mn2+ but not by Mg2+. The ribonuclease is thermosensitive and has maximal activity at pH 7.5. These properties distinguish the Artemia salina ribonuclease from other eukaryotic ribonucleases already reported. The high activity and specificity of this ribonuclease on poly(U) may suggest a role for this enzyme in the processing of the messenger RNA.
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PMID:Purification and properties of a ribonuclease induced during the early larval development of Artemia salina. 71 Apr 39

DNA-dependent RNA polymerase class C (or III) has been solubilized from either uninfected or adenovirus-2-infected HeLa cells and purified by chromatography on phosphocellulose, DNA-cellulose, CM-Sephadex and DEAE-Sephadex. The last column separated the enzyme into three forms CI, CII and CIII, which were completely free of RNA polymerases class A and B and of DNase and RNase. The total and the relative amount of these different enzyme C forms did not vary whether purified from uninfected or infected cells. Irrespective of the stage of purification, the three enzyme forms transcribed deproteinized adenovirus-2DNA very efficiently. This transcription was highly sensitive to elevated ionic strength (especially in the presence of Mg2+) and was accompanied by continuous reinitiation as shown by adding poly(rI), a potent inhibitor of initiation. In addition heparin-resistant initiation complexes could be formed at elevated temperature. The RNA synthesized in vitro on deproteinized intact adenovirus-2 DNA by the different forms of RNA polymerase class C, has been characterized. Analysis of the transcripts by gel electrophoresis, RNA self-annealing, hybridization to separated adenovirus-2 DNA strands and to restriction endonuclease (BamHI, HindIII), adenovirus-2 DNA fragments have demonstrated that restriction endonuclease (BamHI, HindIII), adenovirus-2 DNA fragments have demonstrated that the various regions of the adenovirus-2 genome were randomly transcribed. In addition, hybridization of RNA transcripts labelled at their 5' end by either [gamma32P]ATP or [gamma-32P]GTP indicated that not only elongation but also initiation occurred randomly through the entire adenovirus-2 genome, irrespective of the form of the enzyme and of the origin of the cells (normal or infected). The results are discussed in terms of the components which are possibly involved in specific transcription.
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PMID:Transcription in vitro of adenovirus-2 DNA by RNA polymerases class C purified from uninfected and adenovirus-infected HeLa cells. 71 Apr 51

Polyriboadenylate polymerase was isolated from Escherichia coli PR7 (RNase I-, pnp) in good yield and high purity. The enzyme catalyzes the polymerization of ATP and ADP. These polymerizations show an initial lag which can be removed by the addition of poly(A). However, poly(A) does not function as a primer. UDP and CDP can also serve as substrates but with decreased efficiency. The polymerization of CDP is enhanced by the presence of an oligonucleotide which again does not function as a primer. Polymerization of [gamma-32P]ATP or [beta-32P]ADP result in products with no radioactivity. The product formed from [alpha-32P]ATP on hydrolysis with alkali yields labeled pAp and 2',3'-AMP; thus the enzyme synthesizes poly(A) chains de novo. During the polymerization of ATP, no burst of free ADP can be detected and the time course of phosphate release from ATP ro ADP follows very closely the kinetics of polymerization. dATP and dADP are effective inhibitors of poly(A) synthesis from either ATP or ADP. Sulfhydryl reagents inhibit only the polymerization of ATP and the inhibition is fully reversed by dithiothreitol. However, the enzyme can be protected from sulfhydryl reagents by preincubation with either ATP or ADP in the absence of Mg2+ which is required for polymerization. Studies using acrylamide gel electrophoresis indicate that the polymerization activity with either ATP or nucleoside diphosphates resides in the same protein. The enzyme catalyzes the following exchanges: 32Pi into ADP, 32Pi into ATP, and [14C] ADP into ATP in the presence of phosphate. While the enzyme catalyzes the phosphorolysis of its own product, (pAp-(Ap)nA), it fails to cleave the dephosphorylated product, (Ap(Ap)nA), or ribosomal RNA or tRNA in the presence of inorganic phosphate. The differences and similarities between poly(A) polymerase and polynucleotide phosphorylase are discussed. Based on the 32P exchange studies and other properties of poly(A) polymerase, a plausible mechanism for its action is proposed.
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PMID:Further studies on the isolation and properties of polyriboadenylate polymerase from Escherichia coli PR7 (RNase I-, pnp). 78 66

Treatment of Escherichia coli with the antimicrobial agent N-dodecyldiethanolamine results in damage to the cytoplasmic membrane and rapid release of components of the metabolic pool. A slower secondary release then takes place. The material in the secondary release contains mainly low molecular compounds, nucleotides and nucleosides derived from the breakdown of ribosomal RNA. Some transfer RNA is also released. Breakdown of RNA occurs as a result of activation of the 'latent' ribonuclease I. Breakdown is inhibited by the ribonuclease inhibitors Ca2+ and Mg2+ and does not occur in a ribonuclease I-deficient strain of E. coli.
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PMID:Antimicrobial action of dodecyldiethanolamine: activation of ribonuclease I in Escherichia coli. 80 Oct 34


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