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)

Nuclear RNP from Triturus oocytes is organized as strings of beads which can be converted into 20-nm-diameter monoparticles with mild RNase treatment or into 5-nm-thick linear fibrils with low salt treatment. The protein component comprises a heterogeneous size-range of polypeptides which differ from the polypeptides of the other nucleoproteins of oocytes. The RNA is of high molecular weight, sediments mostly in excess of 50 S, and is capable of assuming considerable secondary structure. Duplex regions in the form of hairpin loops are present and may serve as focal points in the condensation of the RNP transcript fibres to generate the periodic beaded structure. The structure of the beads may be maintained by means of protein-protein interaction since at salt concentrations between 1 and 2 M NaC1 all of the proteins are released in a cooperative manner as various sized aggregates which sediment at 15-30 s. There are no specific proteins obviously peculiar to either the beaded or the fibrillar RNP configuration. The various properties of nuclear RNP are compared with those of chromatin.
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PMID:The structure of nuclear ribonucleoprotein of amphibian oocytes. 56 Oct 88

The diazonium salt of 5'-(4-aminophenyl phosphoryl)-uridine 2'(3')-phosphate reacts stoichiometrically with pancreatic ribonuclease and modifies only one tyrosyl residue, which was identified as Tyr 73 in the amino acid sequence. The modification does not inhibit the biological activity of RNAase on ribonucleic acid, although a large change in the binding constant towards cytidine cyclic phosphate was observed. The modification can be inhibited by addition of the competitive inhibitor cytidine 2'(3')5'-diphosphate and may indicate that Tyr 73 is the most exposed residue or has a unique reactivity towards this reactive substrate analog.
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PMID:Modification of a specific tyrosine residue of ribonuclease A with a diazonium inhibitor analog. 56 34

The trimerization constants of glucagon at pH 10.6 in 0.76 M K2HPO4 have been calculated from circular dichroism data between 5 and 50 degrees C. The free energy, enthalpy, and entropy of transfer have been evaluated from the current results and published data in 0.20 M phosphate. The free energies of transfer are derived completely from an increase in the entropy of transfer, since the enthalpy of transfer is less favorable at all temperatures. These parameters are compared with those of various model groups and compounds: CH2, peptide, methane, ethane, and the 1--13 N-terminal fragments of ribonuclease. The effects of fluoride and chloride on the self-association of glucagon have been compared with that of phosphate at 25 degrees C. These effects are consistent with the binding of approximately one molecule of salt to the trimer and a systematic decrease in the number of water molecules bound to the trimer compared to the monomer for the series K2HPO4, KF, and KCl.
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PMID:Effects of Hofmeister salts on the self-association of glucagon. 64 94

Rat liver rough microsomes (RM) contain two integral membrane proteins which are not found in smooth microsomes (SM) and appear to be related to the presence of ribosome-binding sites. These proteins, of molecular weight 65,000 and 63,000, were designated ribophorins I and II, respectively. They were not released from the microsomal membranes by alkali or acid treatment, or when the ribosomes were detached by incubation with puromycin in a high salt medium. The anionic detergent sodium deoxycholate caused solubilization of the ribophorins, but neutral detergents led to their recovery with the sedimentable ribosomes. Ribosomal aggregates containing both ribophorins, but few other membrane proteins, were obtained from RM treated with the nonionic detergent Kyro EOB (2.5 X10(-2) M) in a low ionic strength medium. Sedimentation patterns produced by these aggregates resembled those of large polysomes but were not affected by RNase treatment. The aggregates, however, were dispersed by mild trypsinization (10 microgram trypsin for 30 min at 0 degrees C), incubation with deoxycholate, or in a medium of high salt concentration. These treatments led to a concomitant degradation or release of the ribophorins. It was estimated, from the staining intensity of protein bands in acrylamide gels, that in the Kyro EOB aggregates there were one to two molecules of each ribophorin per ribosome. Sedimentable complexes without ribosomes containing both ribophorins could also be obtained by dissolving RM previously stripped of ribosomes by puromycin-KCl using cholate, a milder detergent than DOC. Electron microscope examination of the residue obtained from RM treated with Kyro EOB showed that the rapidly sedimenting polysome-like aggregates containing the ribophorins consisted of groups of tightly packed ribosomes which were associated with remnants of the microsomal membranes.
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PMID:Proteins of rough microsomal membranes related to ribosome binding. I. Identification of ribophorins I and II, membrane proteins characteristics of rough microsomes. 64 58

The effects of salt, temperature, enzyme to DNA ratio, and heparin challenge on both total RNA synthesis and synthesis from specific promoters are examined using DNA from bacteriophages lambdacb2 and T7. Determination of synthesis from specific promoters is carried out by the fractionation and quantitation on polyethylenimine-cellulose thin-layer chromatograms of the 5'-terminal oligonucleotides produced by digestion of the RNA products with T1 RNase. The major findings of this work are that (1) lambdacb2 promoters are more salt sensitive than T7 promoters and the salt concentration affects individual promoters differently, (2) T7 promoters initiate maximally at 37 degrees C but the transition temperatures of promoters vary and may be dependent on the salt concentration, (3) increasing the enzyme to DNA ratio results in increasing initiations at the promoters on T7 DNA without causing measurable initiation at non-promoters, and (4) T7 and lambdacb2 promoters show differences in stability when challenged with heparin.
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PMID:Selectivity of RNA chain initiation in vitro. 3. Variables affecting initiation of transcription. 66 11

A study was made of the levels of ribonuclease (RNase) in human serum, using 2 independently collected banks of samples from Scripps Clinic and Research Foundation and the Mayo Clinic, each bank representing more than 100 individuals. These serum samples originated from a cross-section of normal individuals, smokers, patients with benign tumours, and patients with a variety of neoplasms. Elevated levels of serum RNase occurred in 68% of the samples from individuals with malignant disease. Elevated levels also occurred in 24% of the samples from individuals with benign tumours and in 38% of the smoker controls from the Mayo Clinic serum bank. Using ion-exchange chromatography, pooled sera from normal individuals and cancer patients were fractionated by differential salt elution. Each pool showed 2 distinct peaks of RNase activity, and both peaks were elevated to the same degree in the cancer serum pools. Similar results were obtained after thin-layer-gel isoelectric focusing of both normal and cancer sera; no new species of RNase could be detected in the sera of patients with malignant diseases. The results suggested a generalized nonspecific increase in serum RNase in these patients.
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PMID:Serum ribonuclease activity in cancer patients. 69 43

A rapid method is described for the simultaneous removal of contaminant ribonuclease activity and isolation of immunoglobulin G from fractionated or whole serum using insolubilized protein A. Protein A, isolated from the Cowan I strain of Staphylococcus aureus, was covalently attached to Sepharose CL-4B resin and used as a specific affinity absorbent for immunoglobulin G. Affinity column-purified immunoglobulin G preparations were examined for the presence of contaminating serum proteins, retention of antibody activity, and retention of antigenic properties. Following chromatography on protein A-Sepharose, immunoglobulin G preparations were devoid of contaminating serum proteins, in particular ribonuclease activity, that are not normally removed using conventional techniques of salt precipitation in combination with ion-exchange chromatography. There was no significant alteration of either antibody activity or antigenic properties of protein A-Sepharose purified immunoglobulin G.
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PMID:The rapid isolation of ribonuclease-free immunoglobulin G by protein A-sepharose affinity chromatography. 72 86

A method for the release of some proteins from Escherichia coli (MRE 600)ribosomes is described, avoiding extraction with denaturing reagents. High-salt-washed, 70-S ribosomes were treated with pancreatic ribonuclease which led to the release of 12 proteins of the larger ribosomal subunit. Separation of released protein was first attempted by gel filtration and by fractionation with (NH4)2SO4. The number and type of the released proteins were identified by sodium dodecyl sulphate-polyacrylamide gels and two-dimensional gel electrophoresis. The method should prove of use in the large scale purification of proteins L1, L7, and L25.
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PMID:Release of certain ribosomal proteins from 70-S Escherichia coli ribosomes by mild ribonuclease digestion. 76 34

RNA transcribed in vitro at low ionic strength, from either rat liver chromatin or DNA, contains a significant amount of structure resistant to RNase in high salt buffer. This is observed with rat liver (form B polymerase) as well as with Escherichia coli RNA polymerase (RNA nucleotidyltransferase; nucleoside triphosphate: RNA nucleotidyltransferase; EC 2.7.7.6). Treatment with RNases specific for either double-stranded or hybrid RNA indicates that resistance to RNase is due to the presence of double-stranded RNA sequences. Denaturation kinetics in the presence or absence of RNase suggest that these sequences are formed by intramolecular base pairing. Their mean length is about 20 to 30 nucleotides, but 15-20% are more than 100 nucleotides long. They contain 60-65% G-C base pairs. The proportion of double-stranded segments is higher in chromatin transcripts than in DNA-templated RNA, and is higher with homologous RNA polymerase than with the bacterial enzyme. On the other hand, chromatin endogenous RNA polymerase, which is unable to initiate transcription, does not synthesize double-stranded RNA. The problem of the location of these sequences is discussed; preliminary results suggest that the 5' end of the RNA transcripts could be enriched in complementary sequences.
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PMID:Double-stranded RNA in chromatin transcripts formed by exogenous RNA polymerase. 77 79

A new procedure for R17 RNA preparation was devised using a 300 liters fermenter. The key factor in processing such a large quantity is the purification of phage particles prior to RNA extraction. The method involves the preparation of 250 liters of crude lysate, condensation of phage particles by the partition method, purification by DEAE-cellulose column, and removal of adherent proteins by a series of high-salt washes. The method permits preparation of approximately 3 g of phage particles free of ribosomal fragments and RNase. Phage RNA extracted in gram quantities using conventional methods often contain phenol. Thus repeated extraction of R17 RNA with salt-alcohol mixture is required.
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PMID:R17 RNA replicase. VI. A large scale preparation of R17 template RNA. 77 22


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