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

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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)

Acid and alkaline RNase activities in serum were measured with yeast RNA as the substrate in normal subjects and in leukemic patients pretreatment and posttreatment, and the acid/alkaline ratios of activities were 0.63 +/- 0.08 (S.D.) (N, 12), 2.28 +/- 0.82 (N, 8), and 0.60 +/- 0.13 (N, 9), respectively. The mean value for the ratio in the pretreated leukemia was significantly higher than that in the other 2 groups (p less than 0.01). By separating these acid and alkaline RNases from normal and leukemic sera by phosphocellulose chromatography, it was further confirmed that acid RNase alone increased markedly in leukemic serum. From serum and leukocytes of leukemic patients, acid RNases were purified about 2000-fold and 300-fold, respectively, by phosphocellulose and Sephadex G-75 chromatography. Both enzymes displayed properties nearly identical with those of normal serum and leukocytes, except that leukemic serum acid RNase had about a 2.4-fold greater affinity for polyuridylate than for polycytidylate as substrate, in contrast to normal serum acid RNase that degraded polycytidylate exclusively. On the other hand acid RNases from serum leukocytes of leukemia showed a similar substrate preference. These results suggest that the high RNase levels of leukemic sera are due to an excessive leakage of acid RNase into the blood stream from abnormal leukocytes.
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PMID:Serum acid ribonuclease in myelogenous leukemia. 2 65

A molecular hybridization technique has been used to quantitatively measure the nucleotide sequence relationships of selected mammalian RNA tumor viruses. Reciprocal cross-hybridization tests were done in which a given radioactively labeled, viral genomic RNA species was annealed with an excess of unlabeled, complementary DNA product synthesized in endogenously instructed reverse transcriptase reactions. Hybrid formation was measured with pancreatic RNase A. Three representative mammalian RNA tumor virus groups were examined: murine viruses, simian viruses, and feline viruses. The results of reciprocal cross-hybridization testing have revealed that the murine viruses consist of four distinctly related subgroups: (i) the Friend leukemia virus/Rauscher leukemia virus subgroup, (ii) the Gross leukemia virus subgroup, (iii) the Moloney sarcoma virus subgroup, and (iv) the Kirsten sarcoma virus subgroup. Simian sarcoma virus, the only simian virus examined, appeared to share limited interspecies sequence relationships with members of the other virus groups and in particular with Kirsten sarcoma virus. Of the two members of the feline virus group tested, Rickard feline sarcoma virus and RD-114, each was placed in a separate, unrelated subgroup. Rickard feline sarcoma virus exhibited limited sequence relatedness with members of the other virus groups, whereas RD-114 exhibited none.
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PMID:Quantitative nucleotide sequence relationships of mammalian RNA tumor viruses. 4 42

We have investigated three aspects of RNA turmor virus replication and cell transformation: (1) the properties of the purified avian and mammalian viral RNA-directed DNA polumerase, (2) some characteristics of the viral 60-70S RNA genome, 30-40S RNA subunits and intracellular viral RNA species, and (3) the interaction of the viral DNA polymerase with its RNA template early during infection and cell transformation by the murine sarcoma-leukemia virus (MSV[MLV]). Avian myeloblastosis virus (AMV) contains two forms of RNA-directed DNA polymerase, alpha, consisting of a single polypeptide of molecular weight 65,000, and alphabeta, consisting of two polypeptides of molecular weights 65,000 and 105,000. The alpha and alphabeta forms of AMV DNA polymerase both possess RNase H activity that requires free end termini on the ribopolymer and can degrade the RNA of the RNA-DNA hybrid in the 3' to 5' and 5' to 3' directions. But, alpha and alphabeta possess a different mode of exoribonuclease activity. While alphabeta RNase H is a processive exoribonuclease that degrades the polynucleotide chain to a core residue before attacking a second chain, alpha RNase H is a random exoribonuclease that releases the polynucleotide after each scission. Highly purified Moloney-MSV(MLV) DNA polymerase has both RNase H activity and the ability to read viral 60-70S RNA. These activities comigrate through five different steps of purification and are present at levels comparable to those found in purified AMV DNA polymerase. The MSV(MLV) 60-70S RNA genome and 35S RNA subunits were shown by periodate oxidationtritiated borohydride reduction to contain adenosine as the major 3'-terminal nucleoside. Poly (A) segments were isolated from viral 60-70S and 35S RNA by treatment with RNase A or RNase T1 and purified by afinity chromatography and gel electrophoresis. Viral poly(A) was shown to be present at the 3' terminus as -G(C,U)A190AOH. The similar sequence reported for poly(A) present in mammalian mRNA suggests that similar mechanisma are involved in the transcription and processing of both cellular and viral DNA sequences. Within transformed cells replicating MSV(MLV), viral 35S and 20S RNA were found in membrane-bound polyribosomes, whereas only 35S RNA was detected in free polyribosomes. The origin and function of 20S RNA is unknown. The early events during rapid infection and cell transformation of mouse 3T6 cells by the Harvey strain of MSV(MLV) were studied. By both autoradiographic analysis and molecular hybridization, viral DNA synthesis was detected in the cytoplasm by 1 hour after infection, reached a maximum at 2 hours, and subsequently decreased. Cytological chase experiments produced evidence that cytoplasmic viral DNA was transported to the nucleus. In situ hybridization experiments using radioactive viral DNA product as a probe demonstrated the rapid association of viral DNA sequences with the chromocenters of interphase nuclei and with the centromeric heterochromatin regions of some chromosomes.
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PMID:Properties of oncornavirus RNA-directed DNA polymerase, the RNA template, and the intracellular products formed early during infection and cell transformation. 5 Sep 2

Particles with the density and enzymatic activity characteristic of known oncornavirus have been previously described in bone marrow cells from patients with leukemia in relapse and in remission. We have confirmed these findings and studied two patients in whom preleukemia was among the diagnostic considerations. Following cultivation of bone marrow from these patients for 1 week in conditioned media with dexamethasone, a high-speed pellet of the supernatant fluid and disrupted cells was prepared and analyzed on a sucrose gradient for enzymatic activity characteristic of RNA-directed DNA polymerase (reverse transcriptase). Peaks of endogenous DNA polymerase activity showing ribonuclease sensitivity and/or stimulation with the synthetic template poly(rC)-(dG)12-18 were demonstrated in both patients at densities of 1.15 to 1.19 and 1.21 to 1.24 g/ml. Subsequently, diagnosis 2 and 4 months after initial evaluation revealed acute myelogenous leukemia and malignant histiocytosis, respectively. Prior studies have suggested a possible etiological significance of such particles in human leukemia. The demonstration of similar particles preceding clinically overt disease in these patients supports this hypothesis and offers the possibility of early diagnosis and treatment.
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PMID:Oncornavirus-like particles from cultured bone marrow cells preceding leukemia and malignant histiocytosis. 5 58

The Moloney murine sarcoma-leukemia virus [M-MSV (MuLV)], propagated at high multiplicity of infection (MOI), was demonstrated previously to contain a native genome mass of 4 X 10(6) daltons as contrasted to a mass of 7 X 10(6) daltons for Moloney murine leukemia virus (M-MuLV). The 4 X 10(6)-dalton classof RNA from M-MSV (MuLV) was examined for base sequence homology with DNA complementary to the 7 X 10(6)-dalton M-MuLV RNA genome. Approximately 86% of the M-MSV (MuLV) was protected from RNase digestion by hybridization, whereas 95% of M-MuLV was protected under identical conditions. These results indicate that the small RNA class of high-MOI M-MSV (MuLV) contains little (perhaps 10%) genetic information not present in M-MuLV. Virtually all of the 1.8 X 10(6)-dalton subunits of M-MSV (MuLV) RNA contained regions of poly(A) since 94% of the RNA bound to oligo(dT) cellulose in 0.5 M KCl. This suggests that the formation of the 1.8 X 10(6)-dalton subunits occurs before their packaging into virions and does not result from hydrolysis of intact 3.5 X 10(6)-dalton subunits by a virion-associated nuclease.
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PMID:Sequence homology between Moloney murine sarcoma virus and Moloney leukemia virus RNA. 5 17

The Friend erythroleukemia cell line T3-C12, which produces Friend murine leukemia virus (F-MuLV) and can be induced to synthesize hemoglobin by dimethyl sulfoxide (DMSO), was monitored for viral RNA-dependent DNA polymerase reverse transcriptase (RT) activity. The amount of viral 60-70S RNA released from DMSO-treated cells was unaffected or increased compared to that from control cells, while RT activity from treated cells was decreased. Accordingly, the specific activity in F-MuLV from DMSO-treated cells expressed as RT/70S RNA was decreased to 8% of the control activity. The 5-bromo-2'-deoxyuridine added to cultures containing DMSO reversed the differentiation process, and the F-MuLV thus treated did not exhibit the reduced RT activity normally observed in DMSO-treated virus. Cell-free F-MuLV incubated with and without DMSO showed the same RT activity, indicating that DMSO itself did not inhibit RT activity. However, when F-MuLV-containing pellets from control and DMSO-treated culture fluids were mixed, there was marked inhibition of the control RT activity, suggesting that RNase hybrid activity was stimulated or that an inhibitor was produced. Assays of F-MuLV-RNase hybrid released from control and DMSO-treated cells showed no difference in activity, indicating that a specific inhibitor of RT was produced or activated. Additions of certain nucleotide triphosphates to RT incubation mixtures did not result in any stimulation of RT activity in DMSO-treated F-MuLV, suggesting that phosphatase was not responsible for the observed inhibition. The results suggested that DMSO treatment of T3-C12 cells caused a reduction in viral RT activity by stimulating the production of an inhibitor, the nature of which is unknown.
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PMID:Viral reverse transcriptase suppression associated with erythroid differentiation of Friend leukemia cells. 6 77

Human ribonucleases were purified from the sera of Hodgkin's disease patients by sequential column chromatography. The purified enzyme interacted with reverse transcriptase of Rauscher leukemia virus and formed an additive complex of Mr = 130,000. RNase and oligo(dG)-directed reverse transcriptase activities were diminished in the complex. The complex could be dissociated with the subsequent restoration of both activities in the presence of spermidine. The molecular weight of the complex suggest that the 2 RNase molecules bind to a single reverse transcriptase molecule.
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PMID:Complexing Rauscher leukemia virus reverse transcriptase with human plasma ribonuclease from Hodgkin's disease patients. 7 69

The interaction of tRNA with the reverse transcriptase (RNA-dependent DNA polymerase) of mammalian RNA viruses, such as Moloney murine leukemia virus and simian sarcoma virus, has been studied. Whereas the purified reverse transcriptase of mammalian viruses sedimented in glycerol gradients as a globular protein with a molecular weight of 70,000, after interaction with tRNA the enzyme cosedimented with a protein of 150,000 molecular weight. The twofold increase in molecular weight could be a result of either two reverse transcriptase molecules complexed with a tRNA or, alternatively, several tRNA molecules bound to a single enzyme polypeptide. The enzyme complexes were dissociated in part upon degradation of the tRNA moiety by pancreatic RNase A. The reverse transcriptase released from virions of Moloney murine leukemia virus, simian sarcoma virus, and avian myeloblastosis virus, by nonionic detergent, migrated faster on glycerol gradients than purified enzyme preparation. This phenomenon was probably due to complex formation between part of the virion enzyme and the tRNA, which is endogenous in virions. Addition of exogenous tRNA was needed, however, to quantitatively complex all the virion reverse transcriptase of Moloney murine leukemia virus and simian sarcoma viruses. The reverse transcriptase of Moloney murine leukemia virus did not show tRNA species specificity in the binding reaction when glycerol gradients were used for assay. Thus, several tRNA species of Escherichia coli, yeast, chicken, and rat origin were able to complex with the enzyme. The species specificity in the interaction between tRNA and avian myeloblastosis virus reverse transcriptase was also examined. We demonstrated that under our experimental conditions, this enzyme binds different tRNA species of E. coli and yeast as well as tRNA of chicken origin.
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PMID:Binding of tRNA to reverse transcriptase of RNA tumor viruses. 7 7

Ribonuclease (Ribonucleate nucleotide 2'-transferase E.C. 2.7.7.17) activity in serum of patients with chronic granulocytic leukaemia measured at pH 4.5-6.0 amounts to more than three times of that in serum of healthy subjects. At pH 6.0-8.0 the elevation of ribonuclease activity in serum of patients with chronic granulocytic leukaemia is less pronounced and amounts to about two times of that in normal ones. Using chromatography on CM Sephadex C-50 column, serum ribonuclease of both normal and chronic granulocytic leukaemia patients was separated into five distinct fractions. In serum of healthy subjects ribonuclease fractions denoted I-V contribute to 10; 21; 29; 22, and 18 percent of the total ribonuclease activity. In the serum of patients with chronic granulocytic leukaemia a decrease in ribonuclease fraction III to merely 17 percent and an increase in contribution of fraction IV to 32 percent of total ribonuclease activity could be observed. The comparison of each individual concentration of fraction in normal and leukaemia patients serum reveals, that ribonuclease fraction IV will increase about 3 times. A less pronounced increase could also be found for fractions I, II and V. However, ribonuclease fraction IV may be supposed to carry more than 50 percent of the whole extra load of ribonuclease present in the serum of chronic granulocytic leukaemia patients.
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PMID:Elevation of an acid ribonuclease in serum of patients with chronic granulocytic leukaemia. 8 84

The genetic complexities of several ribodeoxyviruses were measured by quantitative analysis of unique RNase T1-resistant oligonucleotides from 60-70S viral RNAs. Moloney murine leukemia virus was found to have an RNA complexity of 3.5 x 10(6) daltons, whereas Moloney murine sarcoma virus had a significantly smaller genome size of 2.3 x 10(6). Reticuleondotheliosis and visna virus RNAs had complexities of 3.9 x 10(6), respectively. Analysis of RNase A-resistant oligonucleotides of Rous sarcoma virus RNA gave a complexity of 3.6 x 10(6), similar to that previously obtained with RNase T1-resistant oligonucleotides. Since each of these viruses was found to have a unique sequence genomic complexity near the molecular weight of a single 30-40S viral RNA subunit, it was concluded that ribodeoxyvirus genomes are at least largely polyploid.
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PMID:Genomic complexities of murine leukemia and sarcoma, reticuloendotheliosis, and visna viruses. 17 29


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