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:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cross-linking reaction between diimido esters and ribonuclease has been studied in terms of the yield of cross-linked dimer with optimum activity toward double-stranded RNA. With dimethyl suberimidate the most satisfactory conditions were condensation for 15 min at pH 7.5-8.0 at 21 degrees C with 1.25 mol equiv of the diimido ester and a protein concentration of 6%. The dimer (yield 20%) had 19 unmodified NH2 groups out of a theoretical 20 for a molecule in which two such groups are involved in the cross-linkage; the activity toward poly(A)-poly(U) in 0.14 M salt solution by spectrophotometric assay was 8.5 times that of the monomeric enzyme toward the same substrate.
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PMID:Preparation of cross-linked dimers of pancreatic ribonuclease. 94 78

HeLa cell nuclei, isolated 17 h after infection with human adenovirus type 2 (Ad2), were treated with 200 mM ammonium sulfate. The extract (S200 fraction) contained 50 to 70% of the nonintegrated Ad2 DNA, which was in the form of nucleoprotein complexes. These complexes contained native, intact Ad2 DNA (with the exception of replicative intermediates) and could be partially purified and resolved by velocity gradient centrifugation. Using high-salt (200 mM ammonium sulfate) incubation conditions, more than 95% of the nuclear RNA polymerase activity belonged to class B. About 45% of the class B enzyme molecules bound to DNA in the nuclei (those "engaged" in RNA synthesis) were released from the nuclei in the form of Ad2 transcriptional complexes by treatment with 200 mM ammonium sulfate. At least 90% of the RNA synthesized in high salt in the nuclei or in the S200 fraction was Ad2 specific, and essentially all of this RNA was complementary to the l strand of Ad2 DNA. These findings are compatible with what is known about Ad2-specific RNA synthesis in vivo. The analysis of the RNA synthesized from partially purified transcriptional complexes supports the contention that its transcription is almost entirely asymmetric, and that the asymmetry observed in vivo is not a consequence of the rapid degradation of h-strand transcripts. The RNA synthesized in vitro in the absence of detectable RNase activity sedimented with a maximum size of 35 to 40S. Less than 5% of the nuclear or the S200 fraction RNA polymerase activity was class C when assayed under non-reinitiating conditions. Although much of the RNA synthesized by the class C enzyme was Ad2 specific, 5.5S virus-associated RNA was not the predominant product. The isolation of Ad2 DNA transcriptional complexes provides an attractive system for further characterizing the Ad2 DNA template used for transcription and for studying the regulation of the expression of the Ad2 genome during the productive infection cycle.
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PMID:Characterization of adenovirus type 2 transcriptional complexes isolated from infected HeLa cell nuclei. 95 Jun 90

The permeability of standard Soviet ultrafiltration membranes prepared from cellulose acetates was investigated with respect to biologically active substances (hemoglobin, trypsin, ribonuclease, vitamin B12, hydroxytetracycline) and inorganic salt (KH2PO4). The arrest of a substance by a membrane of a certain structure depended primarily on the size of the substance macromolecule in the solution. The filtration rate was related to the membrane type, pressure gradient and composition of the filtered solution. Potential use of the tested membranes is described.
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PMID:[Permeability of acetylcellulose ultrafiltration membranes with regard to biologically active substances]. 100 67

The binding of taurodeoxycholate to pancreatic lipase and a few other proteins has been studied with equilibrium dialysis and in gel filtration experiments. A three compartment dialysis cell has been used; with this cell, complete equilibration is not necessary for calculation of the binding even at bile salt concentrations above the critical micellar concentration. The results indicate that taurodeoxycholate does not bind to lipase below the critical micellar concentration, that the binding starts in the critical micellar concentration range of the bile salt and reaches around 12 mol taurodeoxycholate per mol of lipase at taurodeoxycholate concentrations well above the critical micellar concentration. Previous results indicating a binding of maximally 1-2 mol taurodeoxycholate/mol lipase were too low, depending on the experimental conditions in which complete equilibration was not obtained. The binding isotherm for taurodeoxycholate to lipase is similar to that for co-lipase; colipase and lipase in mixture bind as much taurodeoxycholate as the sum for the single proteins. Taurodeoxycholate binds to ribonuclease and chymotrypsinogen to a similar extent as to lipase.
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PMID:On the binding of bile salt to pancreatic lipase. 100 92

Until now it has not been possible to obtain nuclear bodies from Escherichia coli after treatment with rifampicin. It was generally assumed that the cross-connections between the DNA double strands which are sensitive towards ribonuclease are destroyed under the influence of inhibitors of RNA synthesis like rifampicin. In this paper a new lysis procedure is described for preparing nuclear bodies from E. coli. These particles differ in some respects, especially in salt sensitivity from those prepared by earlier methods. Using the new lysis method it is also possible to obtain folded chromosomes from cells after treatment with rifampicin. These nuclear bodies can be destroyed by ribonuclease. Therefore, it has to be postulated that a fraction of RNA being sufficient to hold the chromosome in the folded shape is not susceptible to the action of rifampicin.
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PMID:A mild method for the isolation of folded chromosomes from Escherichia coli. 110 41

The rate of regeneration of reduced RNase by glutathione was examined in the presence of several added substances: substrate, phospholipid, other proteins, bacterial ribosomes, and neutral salts. Of these, only neutral salts showed substantial effects. K2HOP4 and (NH4)2SO4 strongly accelerated regeneration, the alkali chlorides showed moderate acceleration or inhibition, while LiBr and KSCN strongly inhibited. The t1/2 for regeneration in 1 M Pi is 4 min compared to 75 min in the absence of Pi; in 0.5 M KSCN t1/2 greater than 100 min. The pattern of specific salt effects is similar to a Hofmeister series. There is a strong parallel between the pattern of specific salt effects on the kinetics of RNase regeneration and the pattern of effects of the same salts on the equilibrium stability of biopolymers. This suggests that the role of salts in the regeneration is to stabilize or destabilize rate-limiting folding intermediates. Pi-accelerated glutathione regenerations showed a broad temperature optimum from 30-37 degrees. In strong contrast with the virtual concentration independence of the Pi-free controls, with Pi = 1 M, both rates and yields of RNase activity were decreased markedly at [RNase] greater than 2 x 10(-6) M. Phosphate and pyrophosphate showed additive, and in some cases, synergistic accelerations. These results suggest that specific ion binding occurs in addition to general solvent effects.
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PMID:Salt effects in the glutathione-facilitated reactivation of reduced bovine pancreatic ribonuclease. 110 5

tRNA-tDNA hybrids from yeast have been isolated. The main step in purification was chromatography on a BD-cellulose column with salt gradients and formamide, which separates the hybrid material from excess DNA. The hybrids were characterized by density centrifugation in CS2SO4 and by treatment with alkali and pancreatic ribonuclease. Experiments in which DNA that had been sheared to different molecular weights was used for hybrid formation suggest that the tRNA cistrons are tandemly arranged and that the external spacer DNA is preserved in the tDNA.
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PMID:Purification of tDNA from yeast. 110 99

Messenger RNA (mRNA) of membrane-bound polysomes in a membrane fraction of WI-38 cells remains associated with the microsomal membranes even after ribosomes and their nascent polypeptide chains are removed by using puromycin in a high salt buffer or by disassembling the ribosomes in a medium of high ionic strength lacking magnesium. mRNA either was specifically labeled in the presence of actinomycin D, or it was recognized by virtue of its affinity for oligo-dT. Poly A segments in bound mRNAs have an electrophoretic mobility in acrylamide gels which is characteristic of cytoplasmic mRNAs and corresponds to 150-200 adenyl residues. Extensive RNase treatment did not lead to release of the poly A segments of membrane-associated mRNA molecules either from an intact membrane fraction or from a membrane fraction previously stripped of ribosomes. On the other hand, RNase treatment led to the release and digestion of the nonpoly A segments of the mRNA molecules, indicating that the site of attachment of mRNA to the ER membranes is located near or at the 3' end of the molecule which contains the poly A. A direct association of mRNAs and endoplasmic reticulum membranes is considered in a modelto explain the assembly of bound polysomes and protein synthesis in a membrane-associated apparatus.
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PMID:Direct association of messenger RNA with microsomal membranes in human diploid fibroblasts. 113 14

The proteins bound to HeLa cell polyribosomal messenger RNA were isolated by subjecting salt-washed, puromycin-disassembled polyribosomes to a limited digestion with pancreatic ribonuclease (ref. 1, Auerbach, S. and Pederson, T. (1975) Biochem. Biophys. Res. Commun. 63, 149-153). Label-chase experiments with radioactive amino acids revealed that the in vivo decay kinetics of the messenger RNA-associated proteins were approximately first-order, with t1/2 equal 13-15 h. The results suggest that HeLa messenger RNA and its specific set of associated proteins do not behave as single units metabolically.
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PMID:Metabolic stability of messenger ribonucleoprotein in HeLa cells. 114 43

In rats treated with DOCA plus high salt or with high salt alone, hypertensive rats with renal vascular lesions showed an incomplete suppression of KRA. Cathepsin activity of rat kidney was higher under high salt loading than in the control. Beta-glucuronidase activity was greatest in rats with renal vascular lesions and smallest in rats fed on normal chow. RNase and DNase activities were greater in rats with renal vascular lesions than in rats without renal vascular lesions under high salt loading. 2) In rats of both sexes SHR showed greater KRA and cathepsin activities than WK rat under high salt loading. In female rats DNase, RNase and beta-GPase activities were greater in SHR than in WK rat under high salt loading. 3) KRA was higher in SHRSP aged 10 months than in SHRSR, though KRA of SHR was smaller than KRA of WK rat. Cathepsin activity was greater in SHRSP than in SHRSR. DNase and beta-NAGA activities were greater in SHR than in WK rat. 4) In 7 weeks of age SHRSR showed more PRC than SHRSP. At the age of 10 months SHRSP showed higher PRC than WK rat. The roles renin and lysosomal enzymes in hypertensive renal vascular lesions were discussed to some extent.
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PMID:Hypertensive vascular lesions and renin or lysosomal enzymes in rats. 115 86


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