Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.4 (ribonuclease)
 6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A strain of Actinomyces odontolyticus, originally isolated from human dental plaque, produced a non-dialyzable, trypsin-sensitive substance that was bactericidal for certain strains of bifidobacteria at 42 degrees C but not at 37 degrees C. Detectable quantities of the bacteriocin were not produced in liquid media. Experimentally useful yields were obtained by extraction from pour plate cultures of producer cells. At 42 degrees C, exponential killing did not occur until indicator cells had doubled at least once. At 37 degrees C, the bacteriocin effected a transient bacteriostasis. Partially purified concentrates were obtained by diethylaminoethyl-cellulose chromatography, and such material was not inactivated by ribonuclease, deoxyribonuclease, or lipase. Pronase, trypsin, and exposure to 100 degrees C for 20 min completely abolished activity. Inhibitory activity was considerably reduced by exposure to a pH of either 3 or 11. Treatment of producer cells with curing agents did not induce a high frequency of non-bacteriocinogenic cells. The odontolyticin was adsorbed by susceptible, as well as resistant, bacteria.
Antimicrob Agents Chemother 1977 Sep
PMID:Bacteriocin from Actinomyces odontolyticus with temperature-dependent killing properties. 90 31

Forty different oligonucleotides were investigated as possible inhibitors of the depolymerizing activity of RNase A. The strongest inhibitors among the diribonucleoside 2'-5' mono- phosphates were: G2'-5'G, C2'-5'G and U2'-5'G, and among the diribonucleoside 3'-5' monophosphates: ApU, ApC and GpU. Of the eight trinucleotides investigated, ApApUp, ApApCp and ApGpUp were the strongest inhibitors. All four dinucleotides studied (ApUp, ApCp, GpUp and GpCp) were very strong inhibitors, ApUp being the strongest one. The results show that the nature of the various bases in the oligonucleotide has an effect on the degree of inhibition, and that the 3' phosphomonoester group increases the binding of the oligonucleotide to RNase A. These inhibitors can be used in physicochemical and biochemical studies of ribonuclease.
Nucleic Acids Res 1977 Sep
PMID:Inhibition of pancreatic ribonuclease by 2'-5' and 3'-5' oligonucleotides. 90 98

A purification method for Semliki Forest virus-specified RNA-dependent RNA polymerase from BHK cells is described. The procedure entails (i) the preparation of a crude cell lysate by Dounce homogenization of cells 3-5 h post-infection, (ii) differential centrifugation to give a 15 000 g 'mitochondrial' pellet, (iii) equilibrium centrifugation on discontinuous sucrose gradients (Friedman et al. 1972) to give a membranous band of density 1-16 g/ml, (iv) solubilization with Triton N-101 and velocity centrifugation to give a 25S solubilized polymerase complex and (v) affinity chromatography through an oligo (dT)-cellulose matrix bearing immobilized 42S virus particle RNA. The overall purification was approx. 360-fold with a 5% recovery of activity. Of the various intermediate fractions in the purfication procedure, only the relatively crude post-nuclear supernatant fraction was competent to synthesize the major single-stranded RNAs found in infected cells. Other fractions incorporated precursor only into replicative intermediate (RI) or replicative from (RF). Analysis of the product RF showed that it was of the same size and could bind to the same extent to oligo (dT)-cellulose as the RF isolated directly from lysates of infected cells. Displacement hybridization and ribonuclease digestion suggested that the purified polymerase could only complete previously initiated progeny positive strands using negative strands as template and, even in its most highly purified form, was still tightly bound to its template. Analysis on polyacrylamide slab gels revealed the presence of three 35S-labelled polypeptides in the purified polymerase preparation, but a polypeptide which had identical electrophoretic mobility to the lowest mol. wt. polypeptide of the purified polymerase was also present in material from mock-fected cells which had been taken through the purification procedure. From these results we conclude that only two virus-specified polypeptides are present in the polymerase. A scheme for the synthesis of these polypeptides is presented in the accompanying paper.
J Gen Virol 1976 Sep
PMID:Purification and polypeptide composition of Semliki Forest virus RNA polymerase. 96 47

The size of the polyadenylate segment of globin messenger RNA isolated from spleens of anaemic rabbits was estimated by comparison of its electrophoretic migration in polyacrylamide gels to that of synthetic poly(A) segments of known lengths. Conditions of enzymic degradation of mRNA with pancreatic ribonuclease and T1 ribonuclease were carefully established in order to ensure complete degradation of the heteropolymeric part of mRNA without affecting the polyadenylate sequence. The poly (A) segments of spleen globin mRNA were found to be 25-90 nucleotides long whilst those of peripheral blood reticulocytes from the same animals were only 10-30 residues long. Since spleen contains young erythroid cells and since anucleated blood reticulocytes constitute a statistically older population of the same cell line, these results support the idea that the poly(A) segment of mRNA shortens when the message ages.
Eur J Biochem 1976 Sep 15
PMID:Globin messenger RNA from anaemic rabbit spleen. Size of its polyadenylate segment. 97 66

The present paper describes intracellular changes in ribonuclease specific activity during Ca2+-induced sporangium formation in the water mold Achyla bisexualis. The enzymes undergo a decrease in activity prior to crosswall formation followed by an increase in activity during spore cleavage. As spore discharge occurs the RNase activity again decreases. A large percentage of the nuclease activity is associated with a lysosomal-like fraction of the cell, but there is also considerably activity associated with nuclear and microsomal fractions. Addition of cycloheximide or actinomycin D at various times during development prevents further decrease or increase in the enzyme activity. Mixing of cell extracts from different developmental stages provides evidence that inhibitors or activators of the enzyme activity are not responsible for the activity levels evident at the different stages. There is a change in the total levels of presumptive mRNA during Ca2+-induced sporangial formation which appears to be associated with the patterns of RNase activity. Utilizing total cellular RNA and Poly(A)+ RNA with the crude ribonuclease preparations, no substrate specificity could be ascertained.
Arch Microbiol 1976 Sep 01
PMID:The development patterns of lysosomal enzyme activities during Ca2+-induced sporangium formation in Achyla bisexualis. III. Ribonucleases. 98 98

An endogenous DNA-synthesizing complex sensitive to ribonuclease has been found in purified preparations of swollen human sperm heads. Incorporation of [3H]dTTP into acid-precipitable material occurred in the presence of actinomycin D and required addition of dGTP, dCTP, dATP, plus Mg++. Polymerization was sensitive to pretreatment of the complex with pancreatic RNase A or Triton X-100. Exogenous activity was elicited by the synthetic template (dT)12--18-(rA)n but not by (dT)12--18-(dA)n or (dT)10. The complex sedimented from a 10,000 X g supernatant by centrifugation at 165,000 X g for 60 min and banded in sucrose at a density of 1.21--1.25 g/cm3. Endogenous RNase-sensitive DNA polymerase activity from cell-free seminal fluid was also detected in a fraction in sucrose at a density of 1.22 g/cm3. This activity was labile to freezing and stimulated by 0.04% Triton X-100, and thus differed from that of sperm heads.
Proc Natl Acad Sci U S A 1975 Sep
PMID:Ribonuclease-sensitive DNA-synthesizing complex in human sperm heads and seminal fluid. 105 11

A general strategy and a specific tactic for affinity purification of polypeptides synthesized on solid supports are desbribed and demonstrated. The desired peptide chains were distinguished from terminated peptide chains before removal from the support by attachment of an affinity reagnet (cysteinyl-methionine) bearing an affinity group (thiol) and a binding group (carboxylic acid). After cleavage from the synthetic support, the affinity-labeled peptides (Cys-Met-peptides) were bound to an affinity receptor (organomercurial-agarose) and thus separated from terminated peptides and all other peptides lacking the affinity group. The desired synthetic peptide was obtained by separation of the affinity reagent (loss of Cys-Met by cyanogen bromide cleavage). This general affinity purification strategy is independent of the length or amino acid sequence of the desired peptide. After assembly of ribonuclease-(111-124)-tetradecapeptide, using radiolabeled acetic anhudride for termination of uncoupled in termediates, essentially all (greater than 98.5%) of the acetylated delection peptides were removed by employing the organomercurial Cys-Met tactic. Similarly, the purity of crude synthetic histone H4-(1-37)-heptatriacontapeptide was increased six-fold by using this tactic to remove terminated peptides. A related dimeric Cys-Met tactic is outlined for affinity purification of peptides containing internal cysteine and methionine residues.
Proc Natl Acad Sci U S A 1976 Sep
PMID:Affinity purification of synthetic peptides. 106 9

The enrichment of tRNA at specific sites with carbon-13 has been accomplished in vivo using a mutant of Escherichia coli. A relaxed strain of E. coli auxotrophic for methionine was grown in a specifically defined medium supplemented with either [14C] or [13C]-methyl labeled methionine. Cells were collected at the end of the log-phase of growth and tRNA was extracted. Analysis of the radioactivity of the [14C]-labeled tRNA established an incorporation ratio of three labeled carbons per tRNA molecule. Incorporation of the [14C]-label in vivo was confined to the methylation of nucleotides as determined by thin layer chromatography of nucleotides resulting from a ribonuclease digestion of [14C]-labeled tRNA. The carbon-13 NMR spectrum of [13C]-enriched tRNA indicated a similar degree of incorporation into the methylated nucleotides by the substantial enhancement of [13C]-methyl NMR signals only. Assignment of signals has been made for the methyl groups of ribothymidine and N7-methylguanosine in E. coli tRNA.
Nucleic Acids Res 1975 Sep
PMID:Utilization of an Escherichia coli mutant for carbon-13 enrichment of tRNA for NMR studies. 110 Dec 25

Polycations, including ribonuclease A, ribonuclease S protein and peptide, spermine, spermidine, and polylysines, enhance unstimulated and stimulated adenylate cyclase activity of beef thyroid membranes at low concentrations and inhibit these activities at high concentrations. Peak polylysine stimulation occurs with degrees of polymerization of 6 to 14, and for large polymers a potency limit for this maximum is reached at 4 X 10(-5) M expressed as lysine residues. Both enhancement and inhibition appear to be due to charge-charge interactions and are abolished by KC1. Polyanions are inhibitory only. The biphasic effect of polycations is seen on basal cyclase activity, occurs with prostaglandin E1- and 5'-guanylyl-imidodiphosphate-stimulated cyclase, but is most striking with thyrotropin. There is little enhancement of F--activated cyclase. The enhancement is not sensitive to changes in pH, Mg2+, or regenerating system and does not correlate with the stability constants between polycations and ATP. We suggest that the polycation effect is a general, electrostatic effect on membrane conformation and is not restricted to a particular receptor domain.
J Biol Chem 1975 Sep 10
PMID:Charge effects in the activation of adenylate cyclase. 115 87

Preparative agarose gel electrophoresis under denaturing conditions has been successfully employed to purify large quantities of ovalbumin mRNA from hen oviducts. The mRNA thus prepared is physically homogeneous based on its migration as a single component on electrophoresis in both analytical acid-urea agarose gels and formamide-containing, neutral polyacrylaminde gels; it also sediments as a single peak in sucrose gradients containing 70% formamide. The mRNA is chemically free of ribosomal RNA contamination since its oligonucleotide fingerprint map after complete T1 ribonuclease digestion contains no detectable specific large oligonucleotide markers of ribosomal RNAs. It is also not contaminated by other biologically active messenger RNAs because, when it is added to the cell-free wheat germ translation system, the only protein product synthesized is ovalbumin as analyzed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and specific immunoprecipitation. Ovalbumin mRNA has a nucleotide composition of 32.3% A, 21.0% G, 25.7% U, and 20.7% C [(A+U)/(G+C) equal 1.41]. The mRNA contains a heterogeneous poly(A) tract ranging from 20 to 140 residues with a number average chain length of 62 adenylate residues. The molecular weight of the sodium salt of the purified mRNA is approximately 650,000 +/- 63,000, corresponding to a chain length of 1890 +/- 180 nucleotides, as determined by electron microscopy under completely denaturing conditions. This value is in close agreement with the values obtained from: (a) sucrose gradient centrifugation in the presence of 70% formamide; (b) evaluation of poly(A) content in the mRNA and the number average chain length of its poly(A) tract; and (c) sedimentation velocity studies in the presence of 3% formaldehyde. When 125I-labeled ovalbumin mRNA is allowed to hybridize with a large excess of chick DNA, the observed kinetics of hybridization reveal no appreciable reaction between the mRNA and the repeated sequences of the chick DNA, although the mRNA appears to be approximately 600 nucleotides longer than necessary to code for ovalbumin. It thus appears that the entire ovalbumin mRNA is primarily transcribed from a unique sequence in the chick genome.
J Biol Chem 1975 Sep 10
PMID:Physical and chemical characterization of purified ovalbumin messenger RNA. 115 96


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>