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)

Uniformly 15N-enriched ribonuclease T1 (RNase T1) was obtained from Escherichia coli by recombinant techniques. Heteronuclear 1H, 15N-shift correlation spectra were recorded utilizing proton detection. Direct 1H, 15N connectivities were established applying the heteronuclear multiple-quantum coherence technique. Additional 1H, 1H-TOCSY or 1H, 1H-NOESY transfer steps allowed for sequential assignments. Nitrogen atoms without directly bonded protons were detected by means of the heteronuclear multiple-bond correlation experiment. Signals emerging from 15NH and 15NH2 groups were distinguished by heteronuclear triple-quantum filtering methods. 119 nitrogen resonances out of the expected 127 were assigned unambiguously; in addition, previously obtained proton assignments were extended. Preliminary 1H, 15N NMR investigation were performed on the RNase-T1-3'GMP inhibitor complex. Results were interpreted with respect to nucleotide binding.
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PMID:Two-dimensional 1H, 15N-NMR investigation of uniformly 15N-labeled ribonuclease T1. Complete assignment of 15N resonances. 190 6

A fluorescent compound has been detected in proteins browned during Maillard reactions with glucose in vitro and shown to be identical to pentosidine, a pentose-derived fluorescent cross-link formed between arginine and lysine residues in collagen (Sell, D. R., and Monnier, V. M. (1989) J. Biol. Chem. 264, 21597-21602). Pentosidine was the major fluorophore formed during nonenzymatic browning of ribonuclease and lysozyme by glucose, but accounted for less than 1% of non-disulfide cross-links in protein dimers formed during the reaction. Pentosidine was formed in greatest yields in reactions of pentoses with lysine and arginine in model systems but was also formed from glucose, fructose, ascorbate, Amadori compounds, 3-deoxyglucosone, and other sugars. Pentosidine was not formed from peroxidized polyunsaturated fatty acids or malondialdehyde. Its formation from carbohydrates was inhibited under nitrogen or anaerobic conditions and by aminoguanidine, an inhibitor of advanced glycation and browning reactions. Pentosidine was detected in human lens proteins, where its concentration increased gradually with age, but it did not exceed trace concentrations (less than or equal to 5 mumol/mol lysine), even in the 80-year-old lens. Although its precise carbohydrate source in vivo is uncertain and it is present in only trace concentrations in tissue proteins, pentosidine appears to be a useful biomarker for assessing cumulative damage to proteins by nonenzymatic browning reactions with carbohydrates.
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PMID:Formation of pentosidine during nonenzymatic browning of proteins by glucose. Identification of glucose and other carbohydrates as possible precursors of pentosidine in vivo. 190 67

The significance of free alkaline ribonuclease (RNase) activity as a criterion of protein metabolism and nutrition in traumatized man is evaluated in this report. Plasma and urinary levels of RNase were measured in severely injured, hypermetabolic patients and in normal controls. Significant increases in the plasma and urinary RNase levels were seen in these polytrauma victims and they were positively correlated. Plasma RNase levels were also significantly related to blood urea nitrogen and daily urinary nitrogen excretion. Urinary clearance of RNase was increased by 220% in trauma victims, although the creatinine clearance was not affected by trauma. In a subgroup of eight patients who were fed intravenously (1.4 times basal energy expenditure calories and 250-300 mg of N per kilogram per day) for 6 days, the daily excretions of urinary RNase, nitrogen, 3-methylhistidine, creatinine, and catecholamines were measured. There was a significant negative correlation between daily urine RNase and nitrogen balance. A general increase in all the metabolic parameters on the first day of feeding was seen, suggesting a nutritional stress superimposed on the trauma-induced metabolic stress. Excretion of RNase, 3-methylhistidine, and creatinine peaked on the first day of feeding and then decreased. The normal levels could not be reached even after 6 days of adequate nutrition. The results suggest that RNase levels could be used as a biomarker of protein metabolism.
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PMID:Nutritional influence on the plasma and urine-free alkaline ribonuclease levels in severe trauma victims. 190 73

Silicosis was produced experimentally in rats by single intratracheal injections of various doses of SiO2 dust. The weight of the lungs as well as the contents of total nitrogen, collagen, nucleic acids (especially RNA), and lipids increased in accordance with the dose and the time interval. Fibrogenic stimulation in vitro was shown by the supernatant of the homogenized lung in the incorporation of proline into incubated granulation tissue or lung fibroblasts. The fibrogenic factor-activity depended more on the time interval after the injection than on the SiO2 dose. Electrophoresis of the soluble proteins in the silicotic rat lungs showed a protein of 16,000 Da, which was dependent on the time interval following SiO2 administration as well as on the dose itself, and which originated from macrophages. This protein was purified by repeated gel-filtration chromatography. It stimulated collagen synthesis in granulation-tissue cells at a concentration of about 10(-10) M in a dose-dependent way. It was acidic by amino acid composition but differed from calmodulin which also increased collagen synthesis in granulation-tissue cells in vitro. The ability of non-fractionated macrophage preparations to stimulate the incorporation of proline into collagen correlated inversely with the gross alkaline RNase activity.
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PMID:Isolation of silica-dependent protein from rat lung with special reference to development of fibrosis. 254 36

Mouse leukemia (P388) cells were incubated in cell culture medium containing nitrogen mustard [2-chloro-N-(2-chloroethyl)-N-methylethanamine] for 4 h. The nucleophosmin immunoband with a molecular weight of 37,000 (p37; other molecular weights are similarly designated) was observed in both control and nitrogen mustard-treated cells. Three additional immunobands with molecular weights of 80,000 (p80), 120,000 (p120), and 230,000 (p230) were identified in the drug-treated cells. The same results were observed with melphalan, but were not detected when mitomycin C, cis-platinum, Adriamycin, or actinomycin D were used. Treatments with DNase and RNase did not alter the molecular weights of these immunobands. These results indicate that the cross-linked products of nucleophosmin were not linked to DNA or RNA. The pI of p80, p120, and p230 is 5.1, which is the same as that of nucleophosmin (p37). The iodinated tryptic peptide map of p80 is identical to that of nucleophosmin. This result indicates that p80 is a dimer cross-linked by nitrogen mustard. The p80 and p120 immunobands were observed in Novikoff hepatoma and in hypertrophic rat liver, but were not detected in normal liver under the same conditions. These results indicate that tumor or proliferating cells have hexameric nucleophosmins which can be cross-linked by nitrogen mustards.
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PMID:Cross-linkage of nucleophosmin in tumor cells by nitrogen mustard. 272 Jun 80

Methods are described that allow DNA to be prepared from widely different yeasts (Candida utilis, Saccharomyces cerevisiae, and Schizosaccharomyces pombe). The methods are reliably reproducible, and the DNA obtained is of appropriate quality for the construction of gene libraries (upper limit of size range consistently 50-150 kbp). In method A, yeast cells are converted into spheroplasts by treatment with a highly purified mixture of enzymes from Trichoderma harzianum, the spheroplasts are lysed in a lauroylsarcosinate/EDTA buffer, and the lysate is incubated with proteinase K and then directly centrifuged through a cesium trifluoroacetate gradient. DNA is recovered from the appropriate fractions by ethanol precipitation, and the redissolved precipitate is incubated with ribonuclease. For the rest of the isolation, two protocols are given, one avoiding and one including phenol/chloroform extraction. In this way, DNA up to about 150 kbp in size can be obtained. In method B, spheroplasts are not made. Yeast cells are broken by grinding under liquid nitrogen and are then worked up in a manner similar to method A, protocol 2. Subsequent steps depend on the purpose for which the DNA is required. Traditional methods of sucrose or salt density gradient centrifugation or agarose gel electrophoresis are applicable for size selection. A sodium iodide/silica matrix technique allows fast and effective DNA recovery from agarose gels.
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PMID:Isolation of DNA from yeasts. 272 83

Extensive 15N-NMR investigations of active-site amino acids were made possible by the solid-phase synthesis of the N-terminal pentadecapeptide of RNase A with selectively 15N-enriched amino acids. On complexation with S-protein a fully active RNase S' complex was obtained. The 15N resonances of the side chains of lysine-7 (N epsilon), glutamine-11 (N gamma), and histidine-12 (N pi, tau) were studied in the free synthetic peptide, in the RNase S' complex and in the nucleotide complexes RNase S' with 2'CMP, 3'CMP, and 5'AMP. The analysis of the 15N-1H couplings, the 15N line broadenings due to proton exchange, and the chemical shift values showed that, while the imidazole ring is directly involved in the peptide-protein interaction, the side chains of Lys-7 and Gln-11 do not contribute to this interaction. In the nucleotide complexes the resonances of His-12 and Gln-11 are shifted downfield. In the 2'CMP complex a doublet for the N tau signal of His-12 indicates a stable H bond between this nitrogen and the phosphate group of nucleotide. The other nucleotide influence the resonances of the imidazole group much less, possibly due to a slightly different orientation of the phosphate group. The downfield shift of the Gln-11 resonance indicates an interaction between the carbonyl oxygen of the amide group and the phosphate moiety of the nucleotide. The only observable effect of nucleotide complexation on the Lys-7 signal is line broadening due to reduced proton exchange. For comparison with the 15N-NMR titration curves of His-12 in RNase S' the 1H-NMR titration curves of RNase A were also recorded. Both shape and pK values were very similar for the 15N and the 1H titration curves. An extensive analysis of the protonation equilibria with several fitting models showed that a mutual interaction of the imidazole groups of the active-site histidines results in flat titration curves. The Hill plots of all resonances of the imidazole rings, including the 15N resonances, show a small inflection in the pH range 5.8-6.4. Since the existence of a diimidazole system is most likely in this pH range, the inflection could be interpreted as a disturbance of the mutual electrostatic interaction of the active-site histidines by a partial H-bond formation between the imidazole groups.
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PMID:15N- and 1H-NMR investigations of the active-site amino acids in semisynthetic RNase S' and RNase A. 283 66

The influence of a variety of clinical and biochemical parameters on the activities in serum of ribonuclease (RNAse) selective for polycytidylic acid (RNAse C) were examined in 90 adult patients with cancer. The clinical data base determined on each patient included: RNAse C level, carcinoembryonic antigen (CEA) level, age, sex, race, presence (or absence of metastases, type of cancer, site of metastasis, renal function blood urea nitrogen [BUN], creatinine), hepatic function (bilirubin, alkaline phosphatase), and nutritional status (percent ideal body weight, percent weight loss, and albumin). Common tumor types studied included: colon (21), lung (18), breast (15), and hepatocellular carcinoma (10). For comparison, 175 nonmalignant control patients were studied to establish the normal range for RNAse. In patients with cancer, RNAse levels were increased in 57% and CEA levels were above 10 ng/dl in 36%. Although patients with BUN greater than 25 mg/dl or creatinine greater than 1.5 mg/dl were not entered on the study, nonetheless, RNAse was significantly (P less than 0.05) associated with both BUN and creatinine. Nutritional status also had an important influence on RNAse levels as both percent weight loss and percent ideal body weight were significantly (P less than 0.05) associated with circulatory RNAse: weight loss resulted in higher RNAse levels. These results account in part for the increased RNAse levels seen in those malignant conditions such as pancreatic and lung cancer commonly associated with weight loss in advanced stage. The possibility that circulatory RNAse C determination will provide a sensitive means for assessing nutritional status in cancer patients will require prospective evaluation.
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PMID:Influence of nutritional status on circulatory ribonuclease C levels in patients with cancer. 298 Nov 45

The chemistry of Maillard or browning reactions of glycated proteins was studied using the model compound, N alpha-formyl-N epsilon-fructoselysine (fFL), an analog of glycated lysine residues in protein. Incubation of fFL (15 mM) at physiological pH and temperature in 0.2 M phosphate buffer resulted in formation of N epsilon-carboxymethyllysine (CML) in about 40% yield after 15 days. CML was formed by oxidative cleavage of fFL between C-2 and C-3 of the carbohydrate chain and erythronic acid (EA) was identified as the split product formed in the reaction. Neither CML nor EA was formed from fFL under a nitrogen atmosphere. The rate of formation of CML was dependent on phosphate concentration in the incubation mixture and the reaction was shown to occur by a free radical mechanism. CML was also identified by amino acid analysis in hydrolysates of both poly-L-lysine and bovine pancreatic ribonuclease glycated in phosphate buffer under air. CML was also detected in human lens proteins and tissue collagens by HPLC and the identification was confirmed by gas chromatography/mass spectroscopy. The presence of both CML and EA in human urine suggests that they are formed by degradation of glycated proteins in vivo. The browning of fFL incubation mixtures proceeded to a greater extent under a nitrogen versus an air atmosphere, suggesting that oxidative degradation of Amadori adducts to form CML may limit the browning reactions of glycated proteins. Since the reaction products, CML and EA, are relatively inert, both chemically and metabolically, oxidative cleavage of Amadori adducts may have a role in limiting the consequences of protein glycation in the body.
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PMID:Identification of N epsilon-carboxymethyllysine as a degradation product of fructoselysine in glycated protein. 308 71

Growth of toxigenic strains of Aspergillus clavatus Des. and Aspergillus flavus Link at 30 degrees C on milled poultry feeds led to a considerable decrease in the protein, oil and crude fibre contents of the feed substrate. A corresponding increase in the free fatty acid fractions of the feeds due to the activities of these microbes was also recorded. Rapid degradation of the feedstuff by both species was recorded at a temperature of 25 degrees C and 30 degrees C and a pH range of 4.8-6.4. When grown on feed infusion broth at 30 degrees C, the highest amounts of mycelial production with sporulation of both fungal species occurred within the 8-day incubation period. A determination of their extra-cellular enzyme profile showed the production of amylases, pectate lyase, cellulases, proteases, lipases, xyalanases, DNase and RNase. All the carbon and nitrogen sources used (except L-sorbose and DL-tryptophan), supported good mycelial growth with sporulation. An optimal C:N ratio of 5.0:4.5 and 7.5:3.0 was recorded for growth and sporulation of A. clavatus. For A. flavus, a C:N ratio of 7.5:4.5 was found best for growth and 5.0:3.0 for sporulation.
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PMID:Toxigenic fungi and the deterioration of Nigerian poultry feeds. 312 47


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