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:3.1.27.4 (ribonuclease)
6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Exposure of ribonuclease (EC 3.1.27.5) to 5% trichloroacetic acid solution is found to partially inactivate the enzyme. This inactivation is a function of time of exposure to trichloroacetic acid and reaches a plateau of about 45% residual activity. Higher concentrations of trichloroacetic acid lead to greater inactivation. Physicochemical properties such as sedimentation coefficient, gel-filtration behaviour and polyacrylamide gel electrophoresis of the trichloroacetic acid-treated enzyme remain unaffected as compared to the untreated enzyme. However, spectrophotometric titration of the trichloroacetic acid-treated enzyme revealed that one of the three 'buried' groups of tyrosine is exposed to the outside surface of the molecule. Near ultraviolet CD spectra supported these observations. Far ultraviolet CD spectra suggested some refolding of the enzyme after trichloroacetic acid treatment. Immunological determinants on the molecule remain unaltered upon trichloroacetic acid treatment. It is concluded that the exposed tyrosine group may be causing a conformational change in the protein and this change may be indirectly responsible for the observed reduction in the activity after trichloroacetic acid treatment.
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PMID:Denaturation studies on bovine pancreatic ribonuclease. Effect of trichloroacetic acid. 683 Aug 11

Circulating M antigen, specific for genus Schistosoma, was previously described in serum, urine, patients' milk, and in serum and urine of animals infected by S. mansoni. The M antigen was thermostable and soluble in trichloroacetic acid. It was not hydrolyzed by protease, ribonuclease, amylase, or neuraminidase but destroyed by sodium metaperiodate. In the present study, we have purified the M ag by using trichloroacetic acid solubility, DEAE Sephadex, and immunoadsorption. The M ag showed a neutral electric charge, a m.w. heterogeneity, and was only stained by periodic acid-Schiff. The composition study revealed M ag was a glycoprotein with a polysaccharide moiety (63% of the molecules) particularly rich in galactose, fucose, glucosamine, and mannose, and with a high molecular ratio of serine and threonine. The presence of O-glycosidic linkage allowed M ag to be considered as a mucin or a mucus glycoprotein-like component. It was localized in the cell wall of the gut of adult worms.
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PMID:Purification, immunochemical, and biologic characterization of the Schistosoma circulating M antigen. 698 17

Glycosylation of N-linked glycoproteins has been stimulated in hen oviduct and bovine pancreas tissue slices by supplementing the tissue culture media with concentrations of dolichylphosphate from 1-100 micrograms/ml. In oviduct, overall incorporation of radioactive sugars into alkali-stable, hot trichloroacetic acid-precipitable material (N-linked glycoproteins) is stimulated approximately 2-fold in dolichylphosphate-supplemented tissues although no stimulation in protein synthesis is observed. Rather, the elevation in glycosylation seems to be a general one involving many protein acceptors. In vitro analysis of microsomal preparations derived from control or dolichylphosphate-supplemented oviduct tissue slices demonstrated a similar enhancement in glycosylation activities that appears to be attributable to an enhanced level of endogenous dolichylphosphate in the microsomes from supplemented tissues. Additionally, when bovine pancreas tissue slices are preincubated with dolichylphosphate and then doubly labeled with [3H]mannose and 14C-labeled amino acids, a 4-fold increase in the ratio of [3H-mannose to 14C-amino acids in secreted ribonuclease is observed relative to the nonsupplemented control. Furthermore, while only 12% of the ribonuclease secreted from control tissue slices specifically binds to concanavalin A-Sepharose, more than 90% of that secreted by dolichylphosphate-supplemented tissue slices binds to the lectin. These data support the notion that dolichylphosphate availability is a limiting factor in the in vivo glycosylation of proteins in these systems.
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PMID:Enhancement of protein glycosylation in tissue slices by dolichylphosphate. 729 17

The exposure of ribonuclease A to trichloroacetic acid was earlier shown to alter the conformation of the protein resulting in reduced enzymatic activity (Sagar, A. J., Subbiah, V., and Pandit, M. W. (1989) Biochim. Biophys. Acta 995, 144-150). We have studied the structure and enzymatic activity of ribonuclease A treated with trichloroacetic acid over a wide range of acid concentrations (0-40%). The far ultraviolet circular dichroism spectra of ribonuclease A, on exposure to acid concentrations less than 10%, indicated an exceptionally high degree of chiral structure. Exposure of ribonuclease A to acid concentrations between 10 and 30% resulted in the formation of a molecule with significant chiral structure (conventionally assigned to residual secondary structure) but reduced tertiary structure (characteristics very similar to those of molten globule). Increased binding of the hydrophobic probe 1-anilinonaphthalene-8-sulfonate to the enzyme treated with 15-30% acid, as compared with the untreated or completely unfolded protein, supported the existence of a state having characteristics of molten globule. Reversed phase high performance liquid chromatography corroborated the data obtained by circular dichroism as well as 1-anilino-naphthalene-8-sulfonate-binding studies. Beyond acid concentrations of 30%, the ribonuclease is completely denatured. The trichloroacetic acid-induced unfolding is shown to be completely reversible.
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PMID:Trichloroacetic acid-induced unfolding of bovine pancreatic ribonuclease. Existence of molten globule-like state. 817 71

Four, widely used, ribonucleases were found to protect their substrates from acid precipitation by causing, evidently, a modification of their physicochemical properties. The protection was dependent on the kind of substrate while the ratio of protective to nucleolytic activity varied widely between the four enzymes. The protection was enhanced by some nucleotides like UMP, CMP and IMP and decreased in the presence of several bivalent ions like Zn++, Co++ and Cu++. It was completely abolished when the substrates were hybridized with their complementary ribohomopolymers. In the case of bovine pancreatic ribonuclease, the part of the molecule which was responsible for the protective activity was localized on the enzyme domain characterized as S-protein, which lacks nucleolytic activity. The observed property of ribonucleases could lead to false data when the measurement of TCA-soluble material is the method used to follow the purification of ribonucleases or to study their activity. It was also found that ribonuclease S-protein enhances the catalytic activity of B. Cereus RNAse. S-protein could potentiate other RNAses activity like onconase, which has recently been used as an anticancer agent.
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PMID:Ribonucleases protect RNA from acid precipitation. 948 43

Chromatin isolated from soybean (Glycine max L., var. Wayne) hypocotyls was capable of catalyzing the polymerization of labeled deoxyribonucleoside triphosphate in the presence of the three other deoxyribonucleoside triphosphates into a trichloroacetic acid-insoluble product. This product was insensitive to base hydrolysis and ribonuclease, but was sensitive to acid hydrolysis and deoxyribonuclease. Chromatin-DNA polymerase required Mg(2+) and all four deoxyribonucleoside triphosphates for maximal activity. Inorganic pyrophosphate and actinomycin D inhibited the polymerase activity, but 2, 4-dichlorophenoxyacetic acid had no effect in vitro. Chromatin from plants previously treated with 2, 4-dichlorophenoxyacetic acid supported a greater level of DNA synthesis than did chromatin from untreated plants.
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PMID:Enhanced deoxyribonucleic Acid polymerase activity of chromatin from soybean hypocotyls treated with 2,4-dichlorophenoxyacetic Acid. 1665 30

The effect of exogenous RNA on many cellular functions has been studied in a variety of eukaryotic cells but there are few reports on macrophages. In the present study, it is demonstrated that cytoplasmatic RNA extracted from rat macrophages stimulated with Escherichia coli lipopolysaccharide (LPS), referred to as L-RNA, induced the release of TNF-alpha and IL-1 from monolayers of peritoneal resident macrophages. The activity of L-RNA was not altered by polymyxin B but was abolished by ribonuclease (RNase) pretreatment, indicating the absence of LPS contamination and that the integrity of the polynucleotide chain is essential for this activity. Both the poly A(-) and poly A(+) fractions obtained from L-RNA applied to oligo(dT)-cellulose chromatography induced TNF-alpha and IL-1 release. The L-RNA-induced cytokine release was inhibited by dexamethasone and seemed to be dependent on protein synthesis since this effect was abolished by cycloheximide or actinomycin-D. The LPS-stimulated macrophages, when pre-incubated with [5-(3)H]-uridine, secreted a trichloroacetic acid (TCA) precipitable material which was sensitive to RNase and KOH hydrolysis, suggesting that the material is RNA. This substance was also released from macrophage monolayers stimulated with IL-1beta but not with TNF-alpha, IL-6 or IL-8. The substance secreted ((3)H-RNA) sediments in the 4-5S region of a 5-20% sucrose gradient. These results show that L-RNA induces cytokine secretion by macrophage monolayers and support the idea that, during inflammation, stimulated macrophages could release RNA which may further induce the release of cytokines by the resident cell population.
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PMID:RNA from LPS-stirnulated macrophages induces the release of tumour necrosis factor-alpha and interleukin-1 by resident macrophages. 1847 60

The nature of the 5' terminus of tobacco vein mottling virus (TVMV) RNA, a member of the potyvirus group, was investigated. Digestion of viral RNA with ribonuclease led to the appearance of a new polypeptide band of apparent molecular weight 24,000 (24 kDa) after electrophoresis on denaturing polyacrylamide gels. Viral RNA was subjected to radioiodination with the protein-specific Bolton-Hunter reagent. Radioactivity cosedimented on sucrose gradients with intact TVMV RNA. Treatment of the 125I-labeled product with the proteinase Pronase resulted in substantial loss of trichloroacetic acid-precipitable radioactivity. A radioactive species of 24 kDa was released when the(125)I-labeled product was subjected to ribonuclease digestion. To localize the point of attachment, the 125I-labeled TVMV RNA was partially hydrolyzed and used as a hybridization probe against four previously described recombinant plasmids containing TVMV cDNA and a fifth plasmid containing additional 5'-terminal sequences. Hybridization was strongest to plasmids containing the most 5'-terminal sequences. Antisera against the five known proteins encoded by TVMV RNA failed to precipitate significant amounts of the new protein. This genome-linked viral protein (VPg) thus constitutes the sixth polypeptide to be associated with TVMV. It also has the largest apparent molecular weight of any RNA-linked VPg reported to date.
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PMID:Identification of a protein covalently linked to the 5' terminus of tobacco vein mottling virus RNA. 1863 44

Legionella pneumophila is an aquatic bacterium that is also the agent of Legionnaires' disease pneumonia. Since L. pneumophila is transmitted directly from the environment to the lung, it is important to understand how legionellae survive at low temperatures. To identify genes that are needed for L. pneumophila growth at low temperature, we screened a population of mutagenized legionellae for strains that are specifically impaired for growth at 17 degrees C. From the 7,400 mutants tested, 11 displayed defects ranging from ca. 10-fold to a complete inability to grow at the low temperature. PCR and sequence analysis were then utilized to identify the genes whose loss had compromised growth. The proteins thereby implicated in low-temperature growth included components of the type II secretion system (LspE, LspG, LspH), a lipid A biosynthetic enzyme (LpxP), a ribonuclease (RNAse R), an RNA helicase (CsdA/DeaD), TCA cycle enzymes (citrate synthase), enzymes linked to fatty acid (FadB) or amino acid (aspartate aminotransferase) catabolism, and two putative membrane proteins that were, based upon their sequences, unlike previously characterized proteins. Given the magnitude of their mutant's defect, the aspartate aminotransferase, RNA helicase, and one of the putative membrane proteins were the factors most critical for L. pneumophila low-temperature growth. Thus, L. pneumophila not only employs some of the same processes and factors as other bacteria do in order to survive at low temperatures (e.g., LpxP, CsdA), but it also appears to possess novel modes of cold adaptation.
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PMID:Mediators of lipid A modification, RNA degradation, and central intermediary metabolism facilitate the growth of Legionella pneumophila at low temperatures. 1976 2

The sequence of poly(adenylic) acid, present at the 3' end of the majority of eukaryotic mRNA molecules, forms the basis of a sensitive technique for the estimation of mRNA content in nucleic acid samples. Under suitable conditions, poly(A) will form RNA-RNA hybrids with poly(U) in vitro. The poly (A) content of RNA samples can therefore be detected by hybridization with saturating amounts of (3)H-poly(U) (1,2). Following the removal of excess (3)H-poly(U) by ribonuclease treatment, the hybrids can be collected by TCA precipitation and quantified by scintillation counting. If the results are compared with data obtained from a parallel experiment using known amounts of poly (A), a value for the poly (A) content of any number of RNA preparations can be obtained. The technique can be used to detect less than 10(-10)g of poly(A).
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PMID:The estimation of mRNA content by poly(u) hybridization. 2137 82


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