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 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

To evaluate some synthetic catalysts that mimic ribonuclease, a quantitative assay has been developed that measures the number of phosphate diester bonds cleaved in a polymeric RNA substrate. This assay involves determining the number of 5'-oligonucleotide termini produced during the cleavage, using polyuridylic acid as the substrate. Samples withdrawn from the kinetic run are treated with venom exonuclease (phosphodiesterase I), and the increase in the concentration of uridine is determined by high-performance liquid chromatography. A related assay has been developed to monitor the catalyzed cleavage of the dinucleotide uridylyl(3'----5') uridine (UpU).
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PMID:An assay to determine the kinetics of RNA cleavage. 258 71

A new and previously undescribed glycoprotein with a molecular weight of 43,000 has been isolated from human urine. This protein, designated GP43; copurified with ribonuclease, which has the same molecular weight, but ribonuclease activity was removed by passage through an affinity column of agarose-5'-(4-aminophenyl phosphoryl) uridine 2'(3') phosphate. GP43 contains about 5.9% neutral sugar, 2.3% hexosamine, and 1.6% sialic acid. A rabbit antibody to the purified GP43 reacted with human urine and serum as well as with the purified GP43. The genetic polymorphism of GP43 was then studied in desialylated human serum samples by urea-polyacrylamide gel isoelectric focusing, followed by immunoblotting with the specific antibody for GP43. Three common phenotypes, designated GP43 1, 1-2, and 2, were easily recognized using this technique and represented homozygosity or heterozygosity for two autosomal codominant alleles, GP43*1 and GP43/2. The frequencies of the GP43*1 and GP43*2 alleles in a Japanese population were 0.7683 and 0.2317, respectively.
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PMID:Biochemical and genetic studies on GP43, a 43-kD glycoprotein detected immunologically in human urine and serum. 262 98

The organization of select proteins within ribonucleoprotein particles containing heterogeneous nuclear and uridine-rich small nuclear RNAs (hnRNP and UsnRNP respectively) was examined by chemical cross-linking and ribonuclease digestion using diagonal two dimensional PAGE and immunoblotting detection systems. Monoclonal antibodies specific for A2, C1 and C2 hnRNP proteins, detected these proteins at gel coordinates which suggested homotypic dimers and trimers of A2 and homotypic trimers, hexamers and larger multimers of C1 and C2. Ribonuclease digestion did not alter the cross-linking properties of hnRNP C1 and C2 proteins but did result in loss of A2 homotypic dimers and trimers. Blots simultaneously reacted with hnRNP specific monoclonal antibodies and autoimmune patient serum (RNP/Sm), or monoclonal antibodies reactive with the U1 snRNP specific 63 kDa protein and/or the UsnRNP common proteins B', B and D revealed no complexes which would indicate interactions between hnRNPs and UsnRNPs. The U1 UsnRNP specific 63 kDa protein appeared not to be cross-linked to UsnRNP common B', B and D proteins. The data also suggested that UsnRNP common protein D was cross-linkable to UsnRNP common proteins D', E and G but not to B' and B. The cross-linking properties of D were unaffected by ribonuclease digestion. In contrast, ribonuclease digestion resulted in an inability to cross-link select complexes containing either B' and B, or p63. The data suggest that both hnRNPs and UsnRNPs are comprised of RNA-dependent and RNA-independent protein-protein interactions.
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PMID:Reversible chemical cross-linking and ribonuclease digestion analysis of the organization of proteins in ribonucleoprotein particles. 323 Dec 14


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