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:3.1.27.4 (ribonuclease)
6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The fixation of CO2 into major classes of RNA in the mouse embryo was studied in culture. Total fixation of CO2 was low at the two-cell stage and no label was found in RNA. Between the eight-cell and morula/early blastocyst stages of development, total fixation increased markedly but decreased again at the late blastocyst stage. On a per cell basis, the level of incorporation of CO2 decreased steadily throughout the preimplantation period. A significant acceleration in the accumulation of 14CO2 into all classes of RNA occurred between eight-celled embryos and morulae/early blastocysts, and this effect was more evident when results were calculated in relation to cell number. At the late blastocyst stage, incorporation of label into RNA decreased on a per embryo and a per cell basis. Most of the label from CO2 was incorporated into the r-RNA fraction at all stages of development and incorporation into s-RNA was always less. The pattern of labelling of RNA with 14CO2 was similar to that previously obtained for the incorporation of [3H]uridine into embryonic RNA, suggesting that most of the CO2 entering the RNA pool may be incorporated into nucleotide bases. The s-RNA and r-RNA fractions were susceptible to digestion with both pancreatic ribonuclease and 0-3 M alkali. Approximately 31% of the label in the TD-RNA fraction remained after hydrolysis with ribonuclease and a similar proportion of the TD-RNA was resistant to alkali treatment. Incorporation of CO2 by morulae/early blastocysts was substantial during culture in substrate-free medium but was increased significantly in medium containing lactate plus pyruvate. Carbon dioxide fixation into RNA was decreased by preculture for 48 hr before incubation in radioactive medium. When compared with freshly collected morulae/early blastocysts, the proportion of the total label in the s-RNA fraction of precultured embryos was low, and a correspondingly greater proportion of the total label was found in the TD-RNA fraction.
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PMID:The incorporation of carbon dioxide into the major classes of RNA during culture of the preimplantation mouse embryo. 124 46

Quantitative affinity chromatography on uridine-5'-(Sepharose-4-aminophenylphosphoryl)-2'(3')-phosphate was developed for the study of binding of ribonuclease species to nucleotide ligands. Elution of the native species ribonuclease-A and -S on the afffinity matrix in 0.4 M ammonium acetate, pH 5.2, containing various amounts of the soluble competing ligand 2'-cytidine monophosphate, reveals an inverse response of elution volume to concentration of soluble ligand. This response conforms to behavior expected for the competing binding equilibria enzyme-soluble ligand and enzyme-insoluble ligand. A-NALYSIS OF ELUTION DATA ALLOWS CALCULATION OF KI and KIM, the dissociation constants, respectively, for the soluble and insoluble protein-ligand complexes. The values of these chromatographically derived constants are similar to values of dissocation constants determined in solution by kinetics of inhibition by 2'-cytidine monophosphate and uridine-5'-(j-aminophenylphosphoryl)-2'(3')-phosphate. Successful competitive elution experiments with [p-F-Phe8]semisynthetic ribonuclease-S' and individual elution trials for [4-F-His12]semisynthetic ribonuclease-S' indicate the utility of the quantitative affinity chromatographic technique for determination of ligand binding properties of ribonuclease derivatives, including inactive species. Nonbiospecific aspects of the interaction of ribonuclease with the affinity matrix in ammonium acetate buffers of concentrations 0.1 M and below were noted, delinating limits of conditions allowing the biospecificity needed for ligand-binding analyses by competitive elution. The dependence of ribonuclease competitive elution behavior on the amount of protein eluted also was examined and related to theoretical considerations in the quantitative application of affinity chromatography.
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PMID:Analysis of ribonuclease-nucleotide interactions by quantitative affinity chromatography. 127 Apr 20

Adenylyl(3'-5')adenosine (ApA) and uridyl(3'-5')uridine (UpU) are hydrolyzed at unprecedentedly large rates by rare earth metal ions at pH 8, 30 degrees C. With 0.01 M Tm(III), the half-lives are 10 min and 51 min, respectively. Potentiality of these ions as catalytic center of artificial ribonuclease is proposed.
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PMID:Rare earth metal ions for unprecedentedly fast RNA hydrolysis. 128 99

The eosinophil cationic protein (ECP), a potent helminthotoxin with considerable neurotoxic activity, was recently shown to also have ribonucleolytic activity. In this work the substrate preference of ECP ribonuclease action was studied in detail. With single-stranded RNA or synthetic polyribonucleotide substrates ECP showed significant but low activity, 70- to 200-fold less than that of bovine RNase A. ECP hydrolyzed RNA more rapidly than it did any synthetic polynucleotide. Poly(U) was degraded more rapidly than poly(C), and poly(A) and double-stranded substrates were extremely resistant. Defined low molecular weight substrates in the form of the 16 dinucleoside phosphates (NpN') and uridine and cytidine 2',3'-cyclic phosphates were tested, and none showed hydrolysis by ECP at a significant rate. The results link ECP ribonucleolytic activity to the 'non-secretory' liver-type enzymes rather than to the 'secretory' pancreatic-type RNases.
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PMID:Ribonuclease activity and substrate preference of human eosinophil cationic protein (ECP). 171 91

The incorporation of 2'-fluoro- and 2'-aminonucleotides into a hammerhead ribozyme was accomplished by automated chemical synthesis. The presence of 2'-fluorouridines, 2'-fluorocytidines, or 2'-aminouridines did not appreciably decrease catalytic efficiency. Incorporation of 2'-aminocytidines decreased ribozyme activity approximately by a factor of 20. The replacement of all adenosines with 2'-fluoroadenosines abolished catalysis in the presence of MgCl2 within the limits of detection, but some activity was retained in the presence of MnCl2. This effect on catalysis was localized to a specific group of adenines within the conserved single-stranded region of the ribozyme. The decrease in catalytic efficiency was caused by a decrease in the rate constant; the Michaelis constant was unaltered. The 2'-fluoro and 2'-amino modifications conferred resistance toward ribonuclease degradation. Ribozymes containing 2'-fluoro- or 2'-aminonucleotides at all uridine and cytidine positions were stabilized against degradation in rabbit serum by a factor of at least 10(3) compared to unmodified ribozyme.
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PMID:Kinetic characterization of ribonuclease-resistant 2'-modified hammerhead ribozymes. 185 67

We have constructed a chimeric toxin composed of Pseudomonas exotoxin A (PE) and the extracellular ribonuclease of Bacillus amyloliquefaciens, barnase. The chimeric protein, termed PE-Bar, reacted with both anti-PE and anti-barnase antisera and had both ADP ribosylation and ribonuclease activities. The chimeric toxin was cytotoxic to the murine fibroblast cell line L929 and to a murine hybridoma resistant to PE. A mutant form of PE-Bar lacking ADP-ribosylating activity was still cytotoxic to L929 cells. Because treatment of cells prelabeld with [3H]uridine resulted in a decrease in their RNA content, we conclude that this cytotoxic effect was due to the ribonuclease activity of barnase molecules that had been translocated to the cytosol. It is now possible to construct chimeric toxins with two or more enzymatic activities that can be delivered to the cytosol of the target cells.
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PMID:Barnase toxin: a new chimeric toxin composed of pseudomonas exotoxin A and barnase. 190 Apr 55

Several investigations have indicated that Tetrahymena pyriformis secretes ribonuclease activity into culture media. The extracellular ribonuclease from strain W has been purified and partially characterized. The molecular weight was determined by gel filtration to be 26,500. The amino acid composition of the enzyme was compared with those of the three intracellular ribonucleases characterized by Trangas, and substantial differences were demonstrated. The extracellular enzyme hydrolyzed both polyadenylic and polyuridylic acids, indicating lack of absolute base specificity. The hydrolysis of polyadenylic acid followed normal Michaelis-Menten kinetics, but substrate inhibition occurred at high concentrations of polyuridylic acid. The hydrolysis of polyuridylic acid was competitively inhibited by 2'- and 3'-cytidine, guanine, and uridine nucleotides, and by 2'AMP. No inhibition of the hydrolysis of Torula yeast RNA was detected. The kinetic properties of the extracellular ribonuclease are compared with those of the intracellular enzymes.
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PMID:Characterization of the extracellular ribonuclease of Tetrahymena pyriformis W. 192 Jan 45

The absorbance peak in the near ultraviolet electron-transfer spectrum of the oxyvanadium constellation in the "transition-state-analogue complexes" obtained by treating the dephospho form of phosphoglucomutase with inorganic vanadate in the presence of either glucose 1-phosphate or glucose 6-phosphate, as described in an accompanying paper [Ray, W. J., Jr., Burgner, J. W., II, & Post, C. B. (1990) Biochemistry (second of four papers in this issue)], is centered at a wavelength of 312 nm. The position of this peak amounts to a change in oscillator frequency of about -5000 cm-1 relative to that of tetrahedral VO4(3-). To provide a rationale for this spectral change, the near ultraviolet spectra of the di- and monoanions of inorganic vanadate and a number of derivatives of these anions are compared with that of vanadium (V) in the enzymic complexes, in terms of both what is observed experimentally and what is expected from crystal field theory. Comparisons in water and in largely anhydrous solvents show that water is not an essential element in the coordination sphere of inorganic vanadate or its mono- or diesters and hence that the coordination number of V(V) in such compounds likely is four. These comparisons also show that loss of solvating water from a 4-coordinate vanadate on binding cannot provide a rationale for the spectra of the enzymic complexes. Other comparisons show that neither the binding of metal ions nor protonation nor the binding of vanadate at a site with an unusually high or an unusually low dielectric constant can provide such a rationale. Further comparisons with vanadates known to be pentacoordinate strongly suggest that the coordination number of V(V) in the transition-state-analogue complexes of phosphoglucomutase does not exceed four. In fact, from the standpoint of crystal field theory the marked red shift observed in the electron-transfer absorbance spectrum of the oxyvanadium constellation in these complexes is more reasonably interpreted in terms of a decreased coordination at vanadium (V), viz., in terms of a weakened bonding between vanadium and one or more of its coordinating oxygens. This decreased coordination could be produced by a physical stretching of the vanadate ester linkage. By contrast, the near ultraviolet spectrum of the transition-state-analogue complex that ribonuclease forms with an adduct of uridine and vanadate [Lindquist, R. N., Lynn, J. L., & Lienhard, G. E. (1973) J. Am. Chem. Soc. 95, 8762] is similar to spectra of pentacoordinate model compounds of vanadium(V).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The oxyvanadium constellation in transition-state-analogue complexes of phosphoglucomutase and ribonuclease. Structural deductions from electron-transfer spectra. 214 Jun 98

We previously demonstrated that pneumococcal extracts contain a highly specific inhibitor of human neutrophil elastase (HNE). We now show that the active inhibitor in these extracts is a high-molecular-weight, heat-stable substance that appears to be RNA, since inhibitory activity of pneumococcal extracts is decreased by incubation with ribonuclease but not by incubation with deoxyribonuclease or proteinase K. Moreover, metabolically labeled ([3H]uridine) pneumococcal RNA, isolated by phenol extraction followed by ethanol precipitation, strongly inhibits HNE. Pneumococcal capsular polysaccharide, although polyanionic, is only weakly inhibitory toward HNE and is not a major source of elastase-inhibitory activity in pneumococcal extracts. On the other hand, the capsule of Haemophilus influenzae type b contains polyribosylribitol phosphate. This highly charged polyanion possesses HNE-inhibitory activity, but only under special circumstances to be discussed below. Pneumococci (type I, type II smooth, type II rough) and H. influenzae (type b) all release HNE-inhibitory activity into their culture medium during growth. By contrast, Klebsiella pneumoniae and Staphylococcus aureus release little (if any) stable HNE-inhibitory activity during growth. We propose that some bacterial pneumonias may spare host tissue because polyanions released by the invading microorganisms (e.g. RNA from autolysing pneumococci) inhibit elastase released from inflammatory neutrophils and thereby modulate accompanying tissue proteolysis. Pneumonias caused by microorganisms that do not release stable polyanionic inhibitors of HNE (e.g., Staphylococcus and Klebsiella) may be correspondingly more injurious to the lung.
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PMID:Inhibition of human neutrophil elastase by bacterial polyanions. 244 47

Only three forms of Kunjin virus-specified RNA were isolated from cytoplasm early after the latent period (about 15 hr) viz., 44 S genomic-sized single-stranded RNA, 20 S double-stranded "replicative form" (RF), and 20-28 S partially ribonuclease-resistant (about 70%) "replicative intermediate" (RI). The RF and RI were resolved by electrophoresis in aqueous-agarose gel only following LiCl fractionation. The RI did not enter urea-polyacrylamide gels. After denaturation of untreated or RNase-treated RI and RF, only 44 S RNA was present in electropherograms. RNA polymerase activity at 8 hr postinfection was detected by in vitro assays of cytoplasmic extracts and reached a maximum at 24 hr, the only major labeled product being RF; a trace amount of free 44 S RNA was also produced. These results, and the kinetics of incorporation of [3H]uridine into RI, RF, and 44 S RNA in pulse and pulse-chase experiments, formed the basis of a model in which flavivirus RF functions as a recycling template for semiconservative and (mainly) asymmetric replication, on which only one nascent strand is synthesized per cycle.
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PMID:Replication strategy of Kunjin virus: evidence for recycling role of replicative form RNA as template in semiconservative and asymmetric replication. 257 39


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