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:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Murine T cell replacing factor (TRF) was purified from a cellfree supernatant of a T cell hybridoma (B151K12) that constitutively produces TRF. Two assay systems for TRF activity were employed: 1) induction of anti-DNP IgG PFC responses in cultures of splenic B cells from DNP-KLH-primed BALB/c mice, and 2) induction of IgM PFC in chronic B cell leukemic cells (BCL1). The purification scheme consisted of ammonium sulfate precipitation, DEAE-cellulose chromatography, Blue-Sepharose chromatography, hydroxylapatite chromatography, gel permeation with fast protein liquid chromatography (FPLC), and disc polyacrylamide gel electrophoresis. Overall, TRF was purified approximately 34,000-fold with a maximum 3.8% recovery of activity, and the specific activity of the purified TRF was approximately 9.6 X 10(4) U/mg. The TRF that is active in these systems is distinct from the other lymphokines such as IL 1, IL 2, BCGFI (now known as BSFp1), and gamma-interferon. The TRF is extremely hydrophobic, with an apparent m.w. of 50,000 to 60,000 on gel permeation chromatography and 18,000 on SDS-PAGE under reducing conditions. Highly purified B151-TRF abrogated the activity by treatment with trypsin but not with RNase. Moreover, it bound to lima bean agglutinin-Sepharose specific for N-acetylgalactosamine residues, indicating that B151-TRF is a glycosylated glycoprotein containing N-acetylgalactosamine residues. The role of N-acetylgalactosamine residues on TRF activity was additionally substantiated by the fact that the addition of appropriate amounts of N-acetylgalactosamine in the assay systems for TRF preferentially induced a profound suppression for TRF-mediated PFC responses.
...
PMID:Purification and physicochemical characterization of murine T cell replacing factor (TRF). 387 Nov 9

A human agent of non-A, non-B hepatitis (Inoculum I) was transmitted to chimpanzees and alterations in liver and lymphocytes were studied by electron microscopy and by cytochemical techniques during the acute phase of the disease. Three types of cytoplasmic alterations, consisting of a membraneous and an amorphous part were observed in the hepatocytes. The density of the amorphous constituent decreased after treatment with pronase, but not after treatment with ribonuclease (RNase) or deoxyribonuclease (DNase). The wall of C-III, but not C-II had fibrils with a periodicity the contrast of which markedly increased after pronase treatment. Cytochemical data suggest that the inclusions (C-I-III) represent a cellular reaction to the infectious agent rather than the virus itself. Intranuclear vermicular inclusions (INI) were observed in hepatocytes and lymphocytes as well, mainly in degenerating cells. Tubuloreticular inclusions (TRS) did not appear in circulating lymphocytes during acute infection; however, they could be induced by human alpha interferon treatment in vitro. Increased numbers of lymphocytes with parallel tubular arrays (PTA) were noted at the peak of serum aminotransferase elevations. The latter two alterations (TRS and PTA) most likely represent immunologic reactions of the host to the infectious agent.
...
PMID:Ultrastructural and cytochemical study of hepatocytes and lymphocytes during experimental non-A, non-B infections in chimpanzees. 393 94

In this study we show that vaccinia virus replication can be sensitive or resistant to interferon (IFN) in the same strain of mouse L cells. When IFN-treated L cells were maintained in suspension culture, infection led to a rapid inhibition of both viral and cellular protein synthesis together with breakdown of viral RNA and of rRNA. When IFN-treated L cells were maintained in monolayer culture, infection did not lead to significant inhibition of viral protein or RNA synthesis and breakdown of viral or of rRNA was not observed. The resistance of vaccinia virus replication to IFN was not dependent on the input multiplicity or state of growth of the cells (actively dividing or resting). Qualitative and quantitative differences in viral transcription and translation were observed between the two virus-cell systems. Our findings are consistent with the hypothesis that the sensitivity or resistance of vaccinia virus to IFN is mediated by specific viral products that act as activators or selective inhibitors of, at least, the dsRNA-dependent ppp(A2'p)nA synthetase/RNase system.
...
PMID:Mode of sensitivity and resistance of vaccinia virus replication to interferon. 395 96

2-5A is an intracellular effector that has been implicated in interferon action, hormonal regulation, and cell growth control. 2-5A action is mediated through its activation of 2-5A-dependent RNase (RNase L, RNase F). Affinity resins [2-5A-cellulose and core (2-5A)-cellulose] were chemically synthesized for purification and immobilization of 2-5A-dependent RNase from mouse L cells and rabbit reticulocyte lysates. The breakdown of poly(U)-[3'-32P]Cp to acid-soluble fragments was demonstrated using the 2-5A-dependent RNase:2-5A -cellulose complex; this activity was enhanced by adding (free) 2-5A. In contrast, RNase activity was measured from the 2-5A-dependent RNase:core (2-5A)-cellulose complex only after the addition of free 2-5A. The rabbit reticulocyte 2-5A-dependent RNase is activated only by tetramer or higher oligomers of 2-5A; therefore there was breakdown of poly(U)-[3'-32P]Cp using core (2-5A)-cellulose-bound reticulocyte 2-5A-dependent RNase after addition of tetramer 2-5A but there was no poly(U) degradation in the presence of trimer 2-5A. The absence of significant general nuclease in the assays was demonstrated by the resistance to breakdown of poly(C)-[3'-32P]Cp (not susceptible to 2-5A-dependent RNase). Moreover, core (2-5A)-cellulose was used to develop a sensitive (subnanomolar) assay for the detection of authentic 2-5A. 2-5A, or the material to be tested, was added to mouse L-cell 2-5A-dependent RNase:core (2-5A)-cellulose complex in the presence of poly(U)-[3'-32P]Cp. The concentration of 2-5A in the sample could be measured from the amount of poly(U) degradation. Several closely related analogs of 2-5A were tested and found to be completely inactive. The technology described herein may be applied to the study of the regulation of 2-5A-dependent RNase, the detection of 2-5A from cells and tissues, and other aspects of the 2-5A system.
...
PMID:Functional analysis of 2-5A-dependent RNase and 2-5a using 2',5'-oligoadenylate-cellulose. 399 10

The enzymatic synthesis and characterization of (RP)-2',5'-AMPS trimer and tetramer (SP)-5'-O-(1-thiotriphosphates) from chirally substituted (SP)-[alpha-35S]ATP alpha S by 2',5'-oligoadenylate synthetase from interferon-treated L cell extracts are described. The (RP)-ATP alpha S isomer is not a substrate for the synthetase. The identification of the trimer and tetramer analogues (molar ratio 70:30) was accomplished by high-performance liquid chromatography and subsequent separation by charge using DEAE-cellulose thin-layer chromatography. The digestion of the analogue by snake venom phosphodiesterase I (SVPD) to [alpha-35S]ATP alpha S and [35S]AMPS but not by T2 RNase demonstrated the presence of the 2',5' linkage. The assignment of RP configuration of the 2',5'-phosphorothiodiester linkage was based on the highly specific stereoselectivity of SVPD for RP diastereomers [Burgers, P. M. J., & Eckstein, F. (1978) Proc. Natl. Acad. Sci. U.S.A. 75, 4978-4800; Bryant, F. R., & Benkovic, S. J. (1979) Biochemistry 18, 2825-2828; Nelson, P. S., Bach, C. T., & Verheyden, J. P. H. (1984) J. Org. Chem. 49, 2314-2317]. This suggests that the synthesis of the phosphorothioate analogues proceeded via inversion of configuration at the chiral phosphorus of (SP)-ATP alpha S. The putative (RP)-2',5'-AMPS tetramer (SP)-5'-O-(1-thiotriphosphate) displaced the 2',5'-p3A4[32P]pCp analogue from 2',5'-oligoadenylate-dependent endonuclease 5 times more efficiently than did equimolar concentrations of authentic 2',5'-adenylate tetramer triphosphate. Furthermore, in studies using the calcium phosphate coprecipitation technique, the 2',5'-phosphorothioate trimer and tetramer analogues inhibited protein synthesis better than did 2',5'-adenylate trimer and tetramer triphosphates.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:2',5'-Oligoadenylates chiral at phosphorus: enzymatic synthesis, properties, and biological activities of 2',5'-phosphorothioate trimer and tetramer analogues synthesized from (SP)-ATP alpha S. 399 75

The regulation of ppp(A2'p)nA-(2-5A)-dependent RNase (RNase L or RNase F) was investigated in NIH 3T3, clone 1 cells using 2-5A-binding and nuclease activity assays. Minimal levels of 2-5A-dependent RNase were detected in actively dividing clone 1 cells; these levels were independently induced by growth arrest or interferon treatment. Accordingly, levels of the RNase were enhanced during growth arrest by confluency regardless of the presence or absence of interferon or antibody to interferon in the media. Measurement of 2-5A-dependent RNase was unaffected by the addition of any of six different proteinase inhibitors to the cells prior to extraction. The expression of 2-5A-dependent RNase in growth-arrested, interferon-treated cells was still relatively low (about one-third to one-half of that found in similarly treated murine Ehrlich ascites tumor cells). Although this amount of 2-5A-dependent RNase could not be detected by 2-5A-mediated ribosomal RNA cleavage, the activity was identified using a more sensitive novel assay for 2-5A-dependent RNase. In addition, introduction of 2-5A or poly(I) X poly(C) into growth-arrested, interferon-treated cells resulted in some inhibition of protein synthesis. The results indicated that the expression of 2-5A-dependent RNase in NIH 3T3, clone 1 cells is regulated under different physiological conditions and that low levels of 2-5A-dependent RNase were insufficient to significantly inhibit encephalomyocarditis virus replication.
...
PMID:Independent regulation of ppp(A2'p)nA-dependent RNase in NIH 3T3, clone 1 cells by growth arrest and interferon treatment. 401 82

Interferon induction by poly(rI).poly(rC) in primary rabbit kidney and mouse L-929 cell cultures was markedly increased if the cells were previously treated with homologous interferon. This priming effect has been established with different times of exposure of the cells to poly(rI).poly(rC), and was most pronounced for short pulses of contact of the polynucleotide with the cells (10 s, 1 min). Treatment of the cells with pancreatic ribonuclease immediately after their exposure to poly(rI).poly(rC) brought about a relatively greater reduction of the interferon response in interferon-primed cells than it did in unprimed cell cultures. Priming of the cells with interferon did not increase cell-binding of poly(rI).poly(rC), whether this cell-binding was measured quantitatively (by radioactivity, upon exposure of the cells to radiolabeled polymer) or qualitatively (by antiviral activity, by assaying the cell extract for virus plaque reduction). Similarly, interferon priming did not alter the sensitivity of cell-associated poly(rI).poly(rC) to extraneous ribonuclease treatment. Finally, priming with interferon did not decrease the rate of degradation of cell-bound poly(rI).poly(rC) by cellular nucleases nor did it increase the anti-nuclease potency of the cells. The exact mechanism by which previous exposure of the cells to interferon enhances subsequent interferon production, induced by either synthetic polynucleotides or viruses, has not yet been resolved.
...
PMID:Studies on the mechanism of the priming effect of interferon on interferon production by cell cultures exposed to poly(rI)-poly(rC). 435 47

Concentrations of the synthetic polymer polyriboinosinic.polyribocytidylic acid that produced no detectable toxicity in normal L cells produced marked cytotoxicity in L cells treated with interferon. This increase in the susceptibility of cells to the toxicity of the polymer was also observed in human cells and secondary mouse embryo cells treated with homologous interferons before exposure to the polynucleotides. The degree of enhancement of toxicity was dependent on the concentration of interferon to which the cells were exposed. The ratio of antiviral activity induced by interferon to enhancement of toxicity by interferon remained constant through about 1000-fold purification. Various interferon preparations induced by viruses or by polyriboinosinic.polyribocytidylic acid in vivo or in vitro, and international reference standard interferons all exhibited enhancement of toxicity. Both enhancement of toxicity and antiviral activity were destroyed by trypsin and by incubation at 56 degrees for 1 hr, did not act on heterologous cells, were not sedimented by ultracentrifugation, and were not inactivated by ribonuclease, deoxyribonuclease, irradiation with ultraviolet light, or exposure to a pH of 2.
...
PMID:Increased susceptibility of cells treated with interferon to the toxicity of polyriboinosinic-polyribocytidylic acid. 450 64

High doses (100-1000 reference units/ml) of alpha or beta interferons are required to inhibit the growth of herpes simplex virus types I and II (HSV-I and HSV-II) in human Chang cells. In contrast, much lower doses (10-100 reference units/ml) of interferon inhibit replication of encephalomyocarditis virus (EMCV) in these cells. In the HSV-infected cells these high doses did not prevent the virus-induced shut off of host protein synthesis. The interferons were more effective in reducing the virus yield of HSV-I than of HSV-II. At the above concentrations they inhibited HSV-I protein synthesis but had little apparent effect on that of HSV-II. Similar amounts of (2'-5')oligo(adenylate)s were synthesised in response to HSV-I, HSV-II and EMCV infection of Chang cells after treatment with alpha or beta interferons. No (i.e. less than 1 nM) (2'-5')oligo(adenylate)s were found in control cells or on virus infection alone. Only low levels of ppp(A2'p)nA-specific rRNA cleavage were observed in the interferon-treated HSV-infected cells. In contrast, high levels were found in response to EMCV, despite the fact that ppp(A2'p)nA accumulated to similar levels with each of the three viruses in these cells. High-performance liquid chromatographic analysis of material from interferon-treated Chang cells 18 h after infection with HSV-I or HSV-II, combined with radiobinding, radioimmune and rRNA cleavage assays, confirmed the presence of ppp(A2'p)2A and ppp(A2'p)3A at greater than nanomolar concentration. In addition, apparently equivalent amounts of two other putative (2'-5')oligo(adenylate) derivatives which compete in the radiobinding and radioimmune assays, were present. These compounds were only weak activators of the ppp(A2'p)nA-dependent RNase and under appropriate conditions were capable of inhibiting the activation of this RNase by authentic ppp(A2'p)nA. The presence of these potentially inhibitory compounds provides a possible explanation for the relatively low levels of activation of the ppp(A2'p)nA-dependent RNase in interferon-treated, HSV-infected Chang cells.
...
PMID:Activation of the ppp(A2'p)nA system in interferon-treated, herpes simplex virus-infected cells and evidence for novel inhibitors of the ppp(A2'p)nA-dependent RNase. 608 28

Human leukocyte interferon (HL-IF) enhanced the growth inhibition of tumor cells by the human peripheral leukocytes. There was a dose relation between the enhancement of the growth inhibition of tumor cells and the antiviral activity of interferon. When the ratio of lymphocyte to tumor cell was 10:1 or 50:1, it was recognized that HL-IF enhanced the growth inhibition of tumor cells by lymphocyte. The heterologous IFs--mouse and rabbit IFs--or heat-inactivated or trypsinized IF did not enhance the growth inhibition of tumor cells by lymphocytes. RNase treatment did not reduce the antiviral activity and the growth inhibition.
...
PMID:[Effect of interferon on the inhibition of tumor cell growth by human peripheral leukocytes]. 615 81


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

---