Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.5 (RNase)
 17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Preparations of human leukocyte interferon obtained by multi-stage purification procedure exhibited ribonuclease activity with the optimum at pH 7.0--7.5. The enzyme possessed the endonuclease action mechanism. Most substances studied for their effect on the RNA-ase activity in human interferon preparations showed many of them to act on the enzyme in the same way as on other ribonucleases. However, dithioerythritie, a reducing agent for disulfide bounds, activated the ribonuclease in the interferon preparation, as distinct from the pancreatic ribonuclease, which was inhibited by this preparation. Patterns of protein and RNA-ase distribution were obtained by electrophoresis in polyacrylamide gel.
 ...
PMID:[Ribonuclease activity in preparations of human leukocyte interferon]. 0 77

Escherichia coli, strain AB 1157, cells are capable of translating human, mouse, and chicken messenter RNA for interferon with production of interferon of the corresponding specifity. This translation occurs in the presence of serum. The activity of the resulting interferon decreased in parallel to dilution of the original mRNA preparation, upon multiple ulitization of the mRNA solution, as well as upon reduction of the interferon- producing activity of cells-donors of mRNA due to prolonged storage of the cells. Unlike animal cells, the bacteria do not require pre-treatment with actinomycin D. The interferon translated by bacteria is inactivated by trypsin and resistant to ribonuclease.
 ...
PMID:Translation by bacterial cells of messenger RNA for interferon of animal origin. 2 28

Although poly(I) is generally considered to be inactive as an interferon inducer, we have found several authentic poly(I) preparations to be effective inducers. Their interferon inducing ability varied considerably from one cell system to another. In human diploid fibroblasts, primed with interferon and superinduced by cycloheximide and actinomycin D, all active poly(I) samples proved nearly as effective in inducing interferon as poly(I).poly(C). In primary rabbit kidney cell cultures, the active poly(I) samples were either as active, or 3 to 30 times less active than poly(I).poly(C). In intact rabbits they were 100 times less active than poly(I).poly(C). Except for one particular sample, all active poly(I) preparations were inferior to poly(I).poly(C) when assayed for interferon induction in interferon-treated mouse L cells; in DEAE-dextran-treated L cells, they induced little, if any, interferon. The poly(I) inducers of interferon were considerably more susceptible to degradation by TI ribonuclease, pancreatic ribonuclease and human serum nuclease(s) than was poly(I).poly(C) when assayed under the same conditions. Due to their limited half-life time in biological fluids, poly(I) analogues such as those described here may offer a greater safety margin in clinical use than poly(I).poly(C).
 ...
PMID:Interferon inducing activity of polyinosinic acid. 9 86

Membrane fractions from chick embryo cells manifesting viral interference mediated by interferon or poly(I)-poly(C) contain high levels of an alkaline ribonuclease. Enhanced RNase activity is not observed when inhibitors of cell protein or RNA synthesis are present during interferon treatment, or when heterologous interferon is used. The RNase associated with comparable membrane fractions from cells treated with mock-interferon is about 1/10 as active, and shows qualitative differences. In principle, divergent views of interferon action may be reconciled to a common mode of action by postulating that viral interference results from a newly induced or activated RNase of cellular origin and proper specificity that acts to reduce the accumulation and functional capacity of newly synthesized viral RNAs, particularly mRNA. Previous data in support of interferon's acting to inhibit virion-derived transcription in vivo are now interpreted as demonstrating enhanced degradation of viral transcripts (mRNA).
 ...
PMID:Interferon action II. Membrane-bound alkaline ribonuclease activity in chick embryo cells manifesting interferon-mediated interference. 16 14

Pretreatment of mouse L cells with interferon (IF) enhanced IF production in response to polyinosinic-polycytidylic acid (poly I-poly C). Post-treatment of cells with IF caused no significant enhancement of IF production. The enhancing effect of IF pretreatment (priming) reached a maximum after incubation with IF (10 or 100 units/ml) for 4-6 hr at 37 C, but this effect was absent when the incubation was done at 4 C. Cells which were incubated for additional several hours at 37 C after IF pretreatment at 4 C did not develop the primed state nor the antiviral state. The presence of protein synthesis inhibitors during the IF pretreatment depressed, though not completely, the development of the primed state. The residual priming effect was lost when the cells were incubated with the inhibitors at 37 C for 2 hr before they were exposed to poly I-poly C. There was no significant difference in the binding rate of poly I-poly C to cells between IF-treated and untreated cells. The degradation rate of cell-bound poly I-poly C and its sensitivity to exogenous pancreatic ribonuclease in the pretreated cells were also similar to those in the untreated cells.
 ...
PMID:Requirement of newly synthesized protein for the priming activity of interferon. 16 22

Incubation of the mouse L-cell-free system with a concentration of pppA2'p5'A2'p5'A [(2'-5')An] just sufficient to inhibit protein synthesis results in formation of a high-molecular-weight, heatlabile inhibitor and enhanced ribonuclease activity and in the rapid breakdown of (2'-5')An to ATP. The (2'-5')An-enhanced ribonuclease activity is also unstable and in the absence of a (2'-5')-An-regenerating system inhibiton of protein synthesis is transient. Although interferon treatment enhances the synthesis of (2'-5')An, the rates of degradation of (2'-5')An and levels of activatible nuclease are similar in extracts prepared from control or interferon-treated cells. Interestingly, the sensitivity of different cell-free systems to (2'-5')An, varies with the source of the cell-free systems and with the methods used in their preparation. There is, however, no obvious correlation between the sensitivities of the system and the rate of breakdown of (2'-5')An. The significance of these results is discussed in relation to a possible control function for the (2'-5')An system in both interferon-treated and control cells.
 ...
PMID:Synthesis and breakdown of pppA2'p5'A2'p5'A and transient inhibiton of protein synthesis in extracts from interferon-treated and control cells. 21 47

In extracts of interferon-treated HeLa cells, RNA covalently linked to double-stranded RNA (dsRNA) is preferentially degraded compared with mRNA not linked in dsRNA. This was established by following the degradation of poly(A)-containing mRNA annealed with poly(U), of poly(C)-containing encephalomyocarditis virus RNA annealed with poly(I), and of the replicative intermediate of the virus isolated from infected cells. In extracts of interferon-treated cells, dsRNA promotes the synthesis of a series of oligonucleotides, designated (2'-5')oligo(A), which in turn activate an endonuclease. Several lines of evidence suggest that the (2'-5')oligo(A) polymerase/endonuclease system is involved in the preferential degradation of mRNA linked to dsRNA. Conditions that prevent synthesis of (2'-5')oligo(A) prevent this preferential degradation, whereas addition of (2'-5')oligo(A) or conditions that favor its synthesis result in degradation of mRNA both linked and not linked to dsRNA. These results are best explained by a localized activation of the endonuclease near the dsRNA region of our model substrates. We propose that in infected cells activation of the endonuclease takes place near the replicative intermediates of RNA viruses. The replicative intermediates of encephalomyocarditis virus promote synthesis of (2'-5')-oligo(A) in extracts of interferon-treated cells and are degraded to a 20S "core" resistant to digestion with RNase A. This mechanism may be responsible for discrimination between viral and cellular mRNA in interferon-treated cells.
 ...
PMID:Mechanism for discrimination between viral and host mRNA in interferon-treated cells. 22 50

Interferon produced by rainbow trout gonadal cells (RTG-2) was partially purified. The physical, chemical, and biological properties of this in vitro produced fish cell interferon were studied. Purification was achieved by ultracentrifugation, molecular sieve gel chromatography, ion exchange chromatography, and polyacrylamide gel electrophoresis. The isoelectric point of RTG-2 interferon, as determined by CM-Sephadex (C-50) chromatography, was 7.1. Filtration through Sephadex G-150 showed that RTG-2 interferon had a molecular weight of 94,000. The partially purified material was not sedimented at 105,000 times g for 2 h at 4 C. The fish cell interferon was non-dialyzable and exhibited heat and pH stability. The partially purified material was inactivated by treatment with trypsin or 2-mercaptoethanol, but was resistant to treatment with deoxyribonuclease or ribonuclease. RTG-2 interferon which was induced by infectious pancreatic necrosis virus exhibited antiviral activity against challenge with infectious hematopoietic necrosis virus or infectious pancreatic necrosis virus. Partially purified RTG-2 interferon exhibited greater species specificity than the crude material.
 ...
PMID:Partial purification and characterization of RTG-2 fish cell interferon. 23 93

Extracts of interferon-treated HeLa cells adsorbed to poly(I) . poly(C)-agarose have been used to synthesize 2'5'oligo(A). This oligonucleotide has been characterized by enzymatic digestion with alkaline phosphatase, snake venom phosphodiesterase, T2 ribonuclease and chromatography on DEAE, and PEI-cellulose. The oligonucleotide inhibits protein synthesis in vitro and activates an endonuclease present in extracts of control and interferon-treated cells. The metabolic stability of 2'5'oligo(A) has been investigated in these cell extracts. The oligonucleotide undergoes rapid degradation, particularly in the absence of ATP and of an energy regenerating system. Furthermore, the 2'5'oligo(A)-activated endonuclease reverts to an inactive state under these conditions, but can be reactivated upon further addition of 2'5'oligo(A). A possible role for the degradation of 2'5'oligo(A) in the mechanism of interferon action is discussed.
 ...
PMID:Metabolic stability of 2' 5'oligo (A) and activity of 2' 5'oligo (A)-dependent endonuclease in extracts of interferon-treated and control HeLa cells. 42 14

The activity of 2',5'-oligoadenylate synthetase, an enzyme recently discovered in interferon-treated cells, was found in lymphocytes from normal mouse spleen that had received neither exogenous interferon nor its inducers. The oligoadenylate synthesized by lymphocyte cell extracts inhibited protein synthesis in rabbit reticulocyte lysates. The oligomers were composed mainly of trimer and were resistant to digestion by T2 ribonuclease. The level of the enzyme in lymphocytes was about 20 to 30% of that in L929 cells treated with interferon. The activity of the enzyme was further enhanced in lymphocytes in vitro by addition of interferon. The 2',5'-oligoadenylate synthetase was distributed among several lymphoid tissues, but was not detected in cell extracts from brain or liver. The enzyme may play an important role in the regulation of the immune system.
 ...
PMID:2',5'-Oligoadenylate synthetase activity in lymphocytes from normal mouse. 50 Jun 92


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