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

---

Query: EC:3.1.26.9 (ribonuclease)
6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The reduction of nucleic acid by an endogenous polynucleotide phosphorylase and ribonuclease in cells of Brevibacterium JM98A (ATCC 29895) was studied. A simple process was developed for the activation of the endogenous RNA-degrading enzyme(s). RNA degradation was activated by the presence of Pi with 14.2 mumol of ribonucleoside 5'-monophosphate per g of cell mass accumulating extracellularly. The optimum pH for degradation of RNA was 10.5 and the optimum temperature was 55 to 60 degrees C. Enzymatic activity was inhibited by the presence of Ca2+, Zn2+, or Mg2+. Although some of the RNA-degrading enzymatic activity was associated with the ribosomal fraction, most was soluble. Both polynucleotide phosphorylase and ribonuclease activities were identified.
...
PMID:Reduction of endogenous nucleic acid in a single-cell protein. 3 4

Atypical eukaryotic RNA polymerase activity was demonstrated in nuclei of Crypthecodinium cohnii, a eukaryote devoid of histones. Nuclei were isolated from growing cultures of this dinoflagellate and assayed for endogenous RNA polymerase (EC 2.7.7.6) activity. There was a biphasic response to Mg2+ with optima at approximately 0.01 and 0.02 M MgCl2, but in contrast to other eukaryotic RNA polymerases, this enzyme activity was inhibited by low MnCl2 concentrations. In the presence of 0.01 M MgCL2 the optimum (NH4)2SO4 concentration was 0.025 M, a concentration at which the nuclei were lysed. Incorporation of [3H]UMP into RNA was inhibited by actinomycin D and dependent on the presence of undergraded DNA, and the reaction product was sensitive to ribonuclease and KOH digestion. Omission of one or more ribonucleoside triphosphates greatly reduced the incorporation. Only a slight enhancement of RNA polymerase activity resulted from the addition of various amounts of native and denatured calf thymus DNA. Spermine caused a marked inhibition while spermidine had little effect on RNA synthesis in the nuclei. Under the optimum conditions described in the present paper the nuclei incorporated approximately 3 pmoles of [3H]UMP/microgram DNA at 25 C for 15 min, and approximately 80% of this activity was inhibited by the eukaryotic RNA polymerase II inhibitor, alpha-amanitin (20 micrograms/ml). A unique situation therefore exists in C. cohnii nuclei, in which absence of histones (a prokaryotic trait) is combined with alpha-amanitin-sensitive RNA polymerase activity (a eukaryotic trait).
...
PMID:RNA synthesis in isolated nuclei of the dinoflagellate Crypthecodinium cohnii. 57 93

A rapid and simple synthesis of pppGpN type /N equals C, U or A/ diribonucleotide derivatives is described by coupling guanosine 2', 3'-cyclic phosphate 5'-triphosphate with the appropriate ribonucleoside in the presence of ribonuclease T-1.
...
PMID:Synthesis of pppGpN type dinucleotide derivatives: the 5' end sequence of some RNAs. 109 17

The presence, in granulocytes, of high levels of nuclease activity makes it difficult to isolate intact RNA from these cells. We have developed a method that allows purification of functional RNA from normal granulocytes as determined by capability for reverse transcription and in vitro translation. We have shown that a considerable amount of ribonuclease activity remains in granulocyte lysates, even after the addition of heparin or vanadyl ribonucleoside complexes. RNA isolated from such lysates demonstrates only minimal binding to oligothymidylic-cellulose and does not serve as a template for reverse transcription or in vitro translation. However, the extraction of frozen granulocytes into phenol in the presence of both heparin and vanadyl ribonucleoside allows the purification of relatively large quantities of RNA, which serves as an excellent template for reverse transcription and in vitro translation. Purification of granulocyte RNA by this method will facilitate study of granulocyte gene expression.
...
PMID:Purification of functional RNA from human granulocytes. 257 34

Dissociation of RNA and DNA from Escherichia coli RNA polymerase in transcription complexes prepared with enzyme molecules located within and near a rho-dependent transcription termination region on bacteriophage T7 D111 DNA has been studied using a membrane filter-binding assay. Rho protein with ATP present mediated rapid (half-time approximately 27 s) simultaneous dissociation of about 50% of both RNA and DNA. RNA molecules were preferentially released from enzyme molecules located within the termination region. Rapid release of RNA and DNA depended on a nucleoside triphosphate but did not depend on sigma factor. Pretreatment of complexes with ribonuclease prevented dissociation of DNA. Nearly simultaneous dissociation of both RNA and DNA was also detected after a lag of 3 min when the isolated transcription complexes were incubated with all four ribonucleoside triphosphates in the absence of rho factor. In this case, release presumably occurred at the rho-independent termination site that is 5990 nucleotides downstream from the A1 promoter. Thus, the dissociation of DNA from RNA polymerase at rho-dependent and rho-independent transcription termination sites is coupled with or occurs spontaneously soon after the release of transcripts at both sites.
...
PMID:Transcription termination factor rho mediates simultaneous release of RNA transcripts and DNA template from complexes with Escherichia coli RNA polymerase. 388 62

Rat liver mitochondria isolated in sucrose-N-tris(hydroxymethyl)methyl-2-aminoethane-sulphonic acid (TES) incorporated [(3)H]UTP into RNA for 1h. Incorporation was inhibited 50% by 1mug of actinomycin D/ml, 1mug of acriflavine/ml and 0.5mug of ethidium bromide/ml but was insensitive to rifampicin, rifamycin SV, streptovarcin and deoxyribonuclease. After the first 10min of incubation, the synthesis was insensitive to ribonuclease. RNA synthesis by mitochondria isolated in sucrose-EDTA was insensitive to actinomycin D and sensitive to ribonuclease during the first 10min of the incubation but thereafter the sensitivities were the same as for mitochondria isolated in sucrose-TES. In a hypo-osmotic medium the relative extent of incorporation of the four ribonucleoside triphosphates into RNA was CTP>UTP=ATP>>GTP. In an iso-osmotic medium the incorporation of CTP and GTP decreased. All four nucleotides were incorporated into RNA in a DNA-dependent process, as indicated by the inhibition by actinomycin D. In addition, CTP and ATP were incorporated into the CCA end of mitochondrial tRNA. ATP was also incorporated into an unidentified acid-insoluble compound, which hydrolysed in alkali to a product that was not ATP, ADP or 5'- or 2(3')-AMP. Atractyloside inhibited the incorporation of ATP into RNA with 50% inhibition at 2-3nmol/mg of protein. The [(3)H]UTP-labelled RNA had peaks of 16S and 13S characteristic of mitochondrial rRNA. In addition a peak at 20-21S was observed as well as heterogeneous RNA sedimenting throughout the gradient. The synthesis of all these species was inhibited by actinomycin D, indicating that rat liver mitochondrial DNA codes for mitochondrial rRNA as well as other as yet unidentified species.
...
PMID:Synthesis of ribonucleic acid by isolated rat liver mitochondria. 440 94

A cytoplasmic, microsomal bound RNA-dependent RNA polymerase has been purified 2500-fold from rabbit reticulocyte lysates. The synthesis of RNA with the purified enzyme is absolutely dependent on the addition of an RNA template. The best template is hemoglobin messenger RNA, while bacteriophage RNA and poly(A,G) are less active, and DNA is completely inactive as a template. With poly(A,G) as a template, only UTP and CTP are incorporated into polynucleotide chains, indicating that the RNA polymerase is an RNA replicase and not a terminal transferase. With messenger RNA as a template, all four ribonucleoside triphosphates are required for maximal activity. The RNA-dependent RNA polymerase reaction is extremely sensitive to low concentrations of heme, rifamycin AF/013, and ribonuclease and resistant to actinomycin D and DNase. The discovery of RNA-directed RNA synthesis in reticulocytes offers an additional site for control of gene expression in mammalian cells and provides a possible mechanism for amplification of the expression of specific genes.
...
PMID:Reticulocyte RNA-dependent RNA polymerase. 451 33

Cytological preparations of Drosophila polytene chromosomes serve as templates for RNA synthesis carried out by exogenous RNA polymerase (Escherichia coli). Incorporation of labeled ribonucleoside triphosphates into RNA may be observed directly by autoradiography. Because of the effects of rifampicin, actinomycin D, ribonuclease, high salt, and the requirement for all four nucleoside triphosphates, we conclude that the labeling observed over chromosomes is due to DNA-dependent RNA polymerase activity. Using this method, one can observe RNA synthesis in vitro on specific chromosome regions due to the activity of exogenous RNA polymerase. We find that much of the RNA synthesis in this system occurs on DNA sequences which appear to be in a nondenatured state.
...
PMID:RNA synthesis by exogenous RNA polymerase on cytological preparations of chromosomes. 457 95

After the incubation of reovirus replicase reaction mixtures (containing labeled ribonucleoside triphosphates), partially double-stranded ribonucleic acid (pdsRNA) products were isolated by cellulose column chromatography followed by precipitation with 2 m NaCl. The pulse-labeled reaction product contained a significantly large amount of pdsRNA that became complete dsRNA as reaction time increased, indicating that pdsRNA was an intermediate of the replicase reaction. The newly synthesized RNA strand ((3)H-labeled) of the pdsRNA was resistant to ribonuclease digestion, suggesting that single-stranded RNA regions were part of a preexistent unlabeled RNA template. These observations, together with the electrophoretic behavior of the pdsRNA in polyacrylamide gel, are consistent with the hypothesis that dsRNA is synthesized by the elongation of a complementary RNA strand upon a preexistent template of single-stranded RNA (i.e., messenger RNA). The direction of the RNA strand elongation was determined by carrying out the replicase reaction in the presence of (3)H-cytidine triphosphate (or (3)H-uridine triphosphate) and adenine triphosphate-alpha-(32)P followed by a chase with excess unlabeled cytidine triphosphate (or uridine triphosphate). The dsRNA product was digested with T1 ribonuclease and the resulting 3'-terminal fragments were isolated by chromatography on a dihydroxyboryl derivative of cellulose. Examination of the ratio of (3)H to (32)P in these fragments indicated that RNA synthesis proceeded from the 5' to 3' terminus.
...
PMID:Reovirus replicase-directed synthesis of double-stranded ribonucleic acid. 467 85

1. Crude extracts of the extreme halophile Halobacterium cutirubrum contain separable DNA-dependent and RNA-dependent RNA polymerases. 2. The RNA-dependent enzyme has been purified about 2800-fold. 3. It requires RNA, preferably of high molecular weight, and all four ribonucleoside triphosphates to incorporate (14)C-labelled nucleoside triphosphate into an acid-insoluble, ribonuclease-sensitive product. 4. Both the stability and activity of the RNA polymerase are relatively insensitive to changes in potassium chloride or sodium chloride concentration, but incorporation is stimulated by both Mg(2+) and Mn(2+). 5. The molecular weight of the enzyme is about 17000-18000.
...
PMID:Nucleic acid enzymology of extremely halophilic bacteria. Halobacterium cutirubrum ribonucleic acid-dependent ribonucleic acid polymerase. 511 74


1 2 3 4 Next >>

---