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:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A novel replicating agent (IFDO) was isolated from ileal fluid. Growth occurred in vitro under aerobic and anaerobic conditions, and was faster at 37 degrees C than at room temperature. The doubling time was 15.8 min. Colonies were dark brown in colour and occurred beneath the surface of agar after conventional surface inoculation. Provisional data indicate that the agent may be a normal intestinal commensal. The agent was remarkably resistant to inactivation by steam at 134 degrees C, formaldehyde and glutaraldehyde; it was relatively resistant to ionising radiation, and it was filterable through membranes with a nominal pore diameter of 10 nm. Such properties, with the exception of growth in cell-free medium, are shared by "unconventional agents" such as those of Creutzfeldt-Jakob disease and scrapie. Further comparison of the properties of the intestinal agent and of slow viruses revealed additional shared characteristics, including resistance to proteinase K and trypsin, and inactivation by guanidine thiocyanate, diethyl pyrocarbonate, phenol and sodium hydroxide. The agent differs from that of scrapie in being inactivated by ethidium bromide, zinc nitrate, EDTA, hydroxylamine in the presence Sarkosyl, and, under certain circumstances, by ribonuclease. Broth cultures of the agent contained particles possessing considerable size heterogeneity. The smaller filterable particles were generally more susceptible to inactivation, did not survive autoclaving, and were inactivated by papaya protease and lipase. It is possible that the replicating agent may be formed by crystallisation from constituents of the medium, and not by a biological process. This does not exclude the postulated relationship to slow viruses.
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PMID:A novel replicating agent isolated from the human intestinal tract having characteristics shared with Creutzfeldt-Jakob and related agents. 265 97

The homology of angiogenin and pancreatic RNase A provides a compelling reason to systematically compare the characteristics of the two proteins using the chemical modification approaches that proved essential to understanding the action of RNase. Reagents specific for histidine, lysine, and arginine markedly decrease the ribonucleolytic activity of angiogenin, much as has been observed for RNase A. Activity is abolished by reduction of the disulfide bonds and is restored by reoxidation. Methionine, tyrosine, and carboxyl group reagents have no significant effect. From the point of view of reactivity, the histidine and lysine residues in angiogenin are severalfold less susceptible to modification than those in RNase A. Arginine reagents, on the other hand, inactivate angiogenin considerably faster than RNase A. Considering specificity, bromoacetate inactivates angiogenin at pH 5.5 by modifying 1.5 histidines, but lysine and arginine reagents are less specific. Thus, 3.8 and 6.3 residues, respectively, are modified by 1-fluoro-2,4-dinitrobenzene and by formaldehyde plus cyanoborohydride, under conditions where activity decreases by approximately 80% in both cases. With phenylglyoxal, 6.7 arginines are lost when there is 92% inactivation. Poly(G) prevents inactivation by lysine and arginine reagents, and phosphate protects against the effects of lysine modification. Thus, the functional consequences of these modifications likely reflect the loss of critical residues rather than general conformational effects.
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PMID:Ribonucleolytic activity of angiogenin: essential histidine, lysine, and arginine residues. 312 7

Randomly dividing cultures of Saccharomyces cerevisiae were briefly exposed to radioactive adenine and then treated successively with dilute acid, ribonuclease, buffered formaldehyde, and NaOH. This treatment was shown to remove virtually all the radioactivity of the labelled cells other than that in DNA. Thus, in subsequent autoradiographs, only cells which had been synthesizing DNA during exposure to the precursor were labelled. The ages of these individuals within the cell cycle were estimated by measuring their sizes. This revealed that incorporation into DNA occurred almost exclusively during the first quarter of the cell cycle, starting with the initial appearance of the bud. This behaviour agreed closely with that of cells growing in artificially synchronized cultures.
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PMID:The timing of deoxyribonucleic acid synthesis in the cell cycle of Saccharomyces cerevisiae. 428 70

Nucleic acid that is extracted from E. coli labeled by a brief pulse of [(3)H]dT and depatured by treatment with heat, formamide, or formaldehyde bands in a region with a density higher than that of single-stranded E. coli DNA in a Cs(2)SO(4) equilibrium density gradient. If treated with alkali or RNase, it then exhibits the density of single-stranded DNA. These results suggest the presence of a short strand of RNA covalently linked to the nascent DNA. Evidence for the presence of covalently linked RNA-DNA molecules is also obtained by pulse labeling with [(3)H]U. Analyses of nascent nucleic acids from cells pulse labeled for various times, and of the molecules with different sizes, support the hypothesis that the short DNA fragments are formed by extension of even shorter RNA chains, which are synthesized on the parental DNA strands and are removed before ligation of the DNA fragments. The synthesis of the RNA segment of the RNA-DNA molecule is much less sensitive to rifampicin than is the synthesis of bulk RNA.
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PMID:RNA-linked nascent DNA fragments in Escherichia coli. 455 61

Aldehyde-fixed rat tissues were variously dehydrated and impregnated in water-miscible 2-hydroxypropyl methacrylate (HPMA) containing 3 to 20 per cent water and 0.1 per cent alpha,alpha-azobisisobutyronitrile as catalyst for subsequent polymerization with ultraviolet light. Heat polymerization was also effective. Blocks of embedded tissue readily gave ultrathin sections, which required staining by uranyl acetate and/or lead stains to give adequate contrast for electron microscopy. The ultrastructure of pancreas, kidney, muscle, and intestine was well preserved by aldehyde fixation alone. Use of postfixation in osmium tetroxide or direct osmium tetroxide fixation was unsatisfactory. The fine structure of aldehyde-fixed liver from fasted rats was well preserved, whereas that from normal rats showed considerable disorganization and collapse, apparently because of extraction of glycogen during the embedding procedure. Enzymatic extraction of proteins by pepsin and of ribonucleic acid by ribonuclease after either formaldehyde or glutaraldehyde fixation was rapidly effected by direct treatment of ultrathin sections with solutions of the enzymes. In contrast, no digestion of chromatin by deoxyribonuclease could be detected. In spite of this present limitation, HPMA appears to have several advantages over earlier water-miscible embedding media for electron microscopy and to be particularly suitable for ultrastructural cytochemistry.
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PMID:Hydroxypropyl methacrylate, a new water-miscible embedding medium for electron microscopy. 585 16

The interphase nucleolus in Allium porrum, as in many of the plant species studied so far, is highly heterogeneous in ultrastructure owing to the presence of coarse, contorted, thread-like structures, or nucleolonemata. Each nucleolonema appears to be sharply twisted and to give rise to a skein within the nucleolar mass. In order to characterize further these nucleolar components, a variety of cytochemical techniques were exploited. For that purpose, specimens were mostly fixed in 4% formaldehyde and stained in the block according to procedures known to reveal the presence of nucleic acids or proteins. Certain specimens were also digested with deoxyribonuclease, ribonuclease or proteinase K before staining. By staining with phosphotungstic acid or bismuth oxynitrate, the presence of a high concentration of proteins can be demonstrated within thin (0.15 micrometer), filamentous structures which are believed to correspond to the outer region of the nucleolonema. Such convoluted formations disappear upon sufficiently long extraction with proteinase K. Using Bernhard's regressive staining technique for chromatin, the distribution of this substance throughout the nucleolar mass was found to match closely that of the nucleolonemata as revealed by several other procedures. As a last test for investigating the cytochemical make-up of the nucleolus, blocks of tissues were stained with 3,3'-diaminobenzidine, a substance known to react specifically with nucleic acids. When such specimens are digested with ribonuclease for 1 h, there persist within the nucleolus, fibrillogranular zones the localization of which is highly reminiscent of that of the nucleolonemata. Combination of ribonuclease hydrolysis with subsequent treatment with proteinase K (30 min) induces the extraction of a large proportion of the nucleolar material, the persisting loose and rather evenly distributed fibrils exhibiting a diamter of 3-5 nm. The possibility is considered that these units may correspond to chromatin fibrils although they have most likely been displaced from their original localization during the extraction procedures. Our cytochemical data suggest that, in Allium porrum, the nucleolonema is approximately 0.3 micrometer in diameter and may consist of a central axis from which chromatin loops project radially. A possible interpretation for the presence of protein-rich, 0.1 micrometer-thick, annular structures throughout the nucleolonemal skein is that the newly synthesized RNP products are accumulated transiently at the extremities of these loops before migrating to the immediately adjacent granular nucleolar zones.
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PMID:An ultracytochemical study of nucleolar organization in meristematic plant cells (Allium porrum). 615 22

Infection of bovine kidney cells with bovine viral diarrhea virus resulted in the synthesis of a single species of virus-specific RNA. Electrophoresis of this RNA on agarose-urea and agarose-formaldehyde gels indicated that it had a molecular weight of 2.9 X 10(6), corresponding to 8,200 bases (8.2 kilobases). This 8.2-kilobase RNA was resistant to RNase A treatment at 1 microgram/ml but was digested at higher concentrations of RNase (10 micrograms/ml). Sedimentation on neutral sucrose gradients indicated that the majority of this RNA (98%) sedimented at 21S, with a small amount sedimenting at 33S. Sedimentation on formaldehyde-containing sucrose gradients resulted in the conversion of all of the RNA to the faster-sedimenting form. At no time after infection were we able to detect virus-specific RNA species of lower molecular weight than the 8.2-kilobase RNA. The implications of these findings with respect to the means of replication of various togaviruses are discussed.
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PMID:Characterization of virus-specific RNA synthesized in bovine cells infected with bovine viral diarrhea virus. 631 Jan 55

Pyridine borane has been reported as a superior reagent over a wide pH range, 5-9, for the reductive methylation of amino groups of proteins with formaldehyde [J. C. Cabacungan , A. I. Ahmed , and R. E. Feeney (1982) Anal. Biochem. 124, 272-278]. It has also been reported to reduce tryptophan to dihydrotryptophan and to inactivate lysozyme in trifluoroacetic acid [M. Kurata , Y. Kikugawa , T. Kuwae , I. Koyama , and T. Takagi (1980) Chem. Pharm . Bull 28, 2274-2275]. In the present study the specificity of pyridine borane for the two different modifications under different reaction conditions has been demonstrated, and extended to the application to the synthesis of protein containing reductively attached carbohydrates. In the acid reduction, pyridine borane selectively reduced all six tryptophans in lysozyme to dihydrotryptophan while all other amino acids remained intact. On similar treatment no cleavage of the carbohydrate moiety from chicken ovomucoid, and no losses of activity of ovomucoid or ribonuclease, two proteins devoid of tryptophan, were observed. Nearly complete methylation of the lysines of lysozyme, chicken ovomucoid, and ribonuclease was achieved with formaldehyde at pH 7.0 after 2 h at room temperature, with the retention of full activity of the protein without any destruction of tryptophan. The same chemistry was applied to covalently attach glucose and lactose to bovine serum albumin. Parameters, including pH, temperature, and methanol, that affect the reactions were investigated. Incremental additions of pyridine borane during the course of the reactions increased the rate of modification. The covalent attachment of sugar to the epsilon-amino group of lysine was demonstrated by the synthesis of N-alpha- acetylglucitollysine and comparison with acid hydrolysates of the bovine serum albumin-sugar derivatives.
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PMID:Pyridine borane as a reducing agent for proteins. 643 Jan 22

1. When rat yolk sacs were incubated in serum-free medium 199, the 125I-labelled forms of both formaldehyde-treated bovine serum albumin and ribonuclease were captured far more rapidly than 125I-labelled polyvinylpyrrolidone. Extensive adsorption of these proteins to the plasma membrane is the main cause of this effect. 2. Quantitative analysis of the adsorptive-phase pinocytosis of these two proteins showed curved Hofstee plots, suggesting either the presence of multiple classes of binding site on the surface of pinocytically-active yolk-sac cells or a single class of binding site that exhibits negative cooperativity in the binding of these proteins. The values of Km were similar, ranging over 0.6-11.8 microM for 125I-labelled ribonuclease and over 0.31-4.7 microM for formaldehyde-treated 125I-labelled albumin. 3. Competitive uptake studies, in which tracer amounts of each of the 125I-labelled proteins were ingested from serum-free medium containing a higher concentration of one of a series of unlabelled proteins, revealed marked differences between the two radiolabelled proteins. These findings suggest that formaldehyde-denatured albumin is captured by binding to hydrophobic binding sites on the plasma membrane whereas ribonuclease is captured by binding to negatively charged sites.
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PMID:Heterogeneity of binding site for adsorptive pinocytosis of simple proteins by rat yolk sacs. 706 May 63

A ribonucleoprotein fraction that contains most of the rapidly labelled hnRNA has been isolated from gently ruptured oocytes of Triturus cristatus. This fraction consists of large aggregates of ribonucleoprotein and has a high (30:1) ratio of protein to RNA. The labelled RNA is contained in ribonucleoprotein particles that have a density of 1.27 g/cm3 in Cs2SO4 gradients (1.39 g/cm3 after formaldehyde fixation in CSCl gradients). Evidence is presented that the particles are associated in vivo with a fibrillar protein network. When the ribonucleoprotein aggregates are treated with ribonuclease, high salt concentration and nonionic detergent, a fibrillar protein residue is produced which contains many species of protein but a few that have electrophoretic characteristics that are identical to major ribonucleoprotein particle proteins. Isolated labelled hnRNA has been shown to bind specifically polypeptides of molecular weight 60 000 and 54 000 that are found in both particle and fibril preparations. In binding assays in vitro, these polypeptides are found to interact with mRNA to a lesser extent and not with rRNA. The isolated 60 000-Mr and 54 000-Mr proteins have the dual ability of forming ribonucleoprotein 'particles' with hnRNA and of polymerizing to generate 10-nm fibrillar structures in the absence of RNA. The possible cellular functions of these proteins are discussed.
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PMID:Interaction of the hnRNA of amphibian oocytes with fibril-forming proteins. 714 Jul 70


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