982 resultados para beta(1 -> 3 : 1 -> 6)-D-glucans
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Spodoptera frugiperda beta-1,3-glucanase (SLam) was purified from larval midgut. It has a molecular mass of 37.5 kDa, an alkaline optimum pH of 9.0, is active against beta-1,3-glucan (laminarin), but cannot hydrolyze yeast beta-1,3-1,6-glucan or other polysaccharides. The enzyme is an endoglucanase with low processivity (0.4), and is not inhibited by high concentrations of substrate. In contrast to other digestive beta-1,3-glucanases from insects, SLam is unable to lyse Saccharomyces cerevisae cells. The cDNA encoding SLam was cloned and sequenced, showing that the protein belongs to glycosyl hydrolase family 16 as other insect glucanases and glucan-binding proteins. Multiple sequence alignment of beta-1,3-glucanases and beta-glucan-binding protein supports the assumption that the beta-1,3-glucanase gene duplicated in the ancestor of mollusks and arthropods. One copy originated the derived beta-1,3-glucanases by the loss of an extended N-terminal region and the beta-glucan-binding proteins by the loss of the catalytic residues. SLam homology modeling suggests that E228 may affect the ionization of the catalytic residues, thus displacing the enzyme pH optimum. SLam antiserum reacts with a single protein in the insect midgut. Immunocytolocalization shows that the enzyme is present in secretory vesicles and glycocalyx from columnar cells. (C) 2010 Elsevier Ltd. All rights reserved.
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β-(1→3)-Glucanases were produced by Trichoderma harzianum Rifai PAMB-86 cultivated on botryosphaeran in a bench-fermenter and optimised by the response surface method. Maximal enzyme titres occurred at 5 days, initial pH 5.5 and aeration of 1.5vvm. β-(1→3)-The β-glucanolytic enzyme complex produced by T. harzianum Rifai PAMB- 86 was fractionated by gel filtration into 2 fractions (F-I, F-II), and employed to produce gluco-oligosaccharides from algal paramylon ((1→3)-β-D-glucan) and lichen pustulan ((1→6)-β-D-glucan). Both enzymes attacked paramylon to the extent of ~15-20% in 30 min releasing glucose and laminaribiose as major end-products, and laminarioligosaccharides of degree of polymerization (DP) ≥3. Only F-I degraded pustulan resulting in ~2% degradation at 30 min, with glucose, gentiobiose and gentio-oligosaccharides of DP ≥4 as major products. The difference in the nature of the hydrolysis products can be explained by the substrate specificities of each enzyme fraction, and the structural differences of the β-D-glucans attacked.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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A versatile and concise approach for the stereoselective synthesis of mono-, di-, and trihydroxylated indolizidines is presented in four to six steps from Cbz-prolinal and a diazophosphonate. The key steps involved a Wolff rearrangement, followed by a stereoselective dihydroxylation/epoxidation reaction, from an alpha,beta-unsaturated diazoketone. The strategy also permits extension to the synthesis of many natural hydroxylated indolizidine alkaloids as demonstrated in the formal synthesis of pumiliotoxin 251D.
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von S. Meyer
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Fil: Matuschka, Daniel von.
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Oligonucleotides consisting of the isonucleoside repeating unit 2′,5′-anhydro-3′-deoxy-3′-(thymin-1-yl)-d-mannitol (4) were synthesized with the monomeric unit 4 incorporated into oligonucleotides as 1′→4′ linkage 4a (oligomer I) or 6′→4′ linkage 4b (oligomer II). The hybrid properties of the two oligonucleotides I and II with their complementary strands were investigated by thermal denaturation and CD spectra. Oligonucleotide I (4a) formed a stable duplex with d(A)14 with a slightly reduced Tm value of 36.6°C, relative to 38.2°C for the control duplex d(T)14/d(A)14, but oligomer II (4b) failed to hybridize with a DNA complementary single strand. The spectrum of the duplex oligomer I/d(A)14 showed a positive CD band at 217 nm and a negative CD band at 248 nm attributable to a B-like conformation. Molecular modeling showed that in the case of oligomer I the C6′ hydroxy group of each unit could be located in the groove area when hybridized to the DNA single strand, which might contribute additional hydrogen bonding to the stability of duplex formation.
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The early growth response 1 (EGR-1) gene product is a transcription factor with role in differentiation and growth. We have previously shown that expression of exogenous EGR-1 in various human tumor cells unexpectedly and markedly reduces growth and tumorigenicity and, conversely, that suppression of endogenous Egr-1 expression by antisense RNA eliminates protein expression, enhances growth, and promotes phenotypic transformation. However, the mechanism of these effects remained unknown. The promoter of human transforming growth factor beta 1 (TGF-beta 1) contains two GC-rich EGR-1 binding sites. We show that expression of EGR-1 in human HT-1080 fibrosarcoma cells uses increased secretion of biologically active TGF-beta 1 in direct proportion (rPearson = 0.96) to the amount of EGR-1 expressed and addition of recombinant human TGF-beta 1 is strongly growth-suppressive for these cells. Addition of monoclonal anti-TGF-beta 1 antibodies to EGR-1-expressing HT-1080 cells completely reverses the growth inhibitory effects of EGR-1. Reporter constructs bearing the EGR-1 binding segment of the TGF-beta 1 promoter was activated 4- to 6-fold relative to a control reporter in either HT-1080 cells that stably expressed or parental cells cotransfected with an EGR-1 expression vector. Expression of delta EGR-1, a mutant that cannot interact with the corepressors, nerve growth factor-activated factor binding proteins NAB1 and NAB2, due to deletion of the repressor domain, exhibited enhanced transactivation of 2- to 3.5-fold over that of wild-type EGR-1 showing that the reporter construct reflected the appropriate in vivo regulatory context. The EGR-1-stimulated transactivation was inhibited by expression of the Wilms tumor suppressor, a known specific DNA-binding competitor. These results indicate that EGR-1 suppresses growth of human HT-1080 fibrosarcoma cells by induction of TGF-beta 1.
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We report the molecular cloning of the first beta-1,3 glucanase from animal tissue. Three peptide sequences were obtained from beta-1,3 glucanase that had been purified from eggs of the sea urchin Strongylocentrotus purpuratus and the gene was cloned by PCR using oligonucleotides deduced from the peptide sequences. The full-length cDNA shows a predicted enzyme structure of 499 aa with a hydrophobic signal sequence. A 3.2-kb message is present in eggs, during early embryogenesis, and in adult gut tissue. A polyclonal antibody to the native 68-kDa enzyme recognizes a single band during early embryogenesis that reappears in the adult gut, and recognizes a 57-kDa fusion protein made from a full-length cDNA clone for beta-1,3 glucanase. The identity of this molecule as beta-1,3 glucanase is confirmed by sequence homology, by the presence of all three peptide sequences in the deduced amino acid sequence, and by the recognition of the bacterial fusion protein by the antibody directed against the native enzyme. Data base searches show significant homology at the amino acid level to beta-1,3 glucanases from two species of bacteria and a clotting factor from the horseshoe crab. The homology with the bacteria is centered in a 304-aa region in which there are seven scattered regions of high homology between the four divergent species. These four species were also found to have two homologous regions in common with more distantly related plant, fungal, and bacterial proteins. A global phylogeny based on these regions strongly suggests that the glucanases are a very ancient family of genes. In particular, there is an especially deep split within genes taken from the bacterial genus Bacillus.
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Els objectius a treballar són: a) Detectar aspectes o variables personals i contextuals que afecten el desenvolupament integral de la xiqueta. b) Conèixer l’impacte que determinades situacions personals o ambientals produeixen en els diferents àmbits del desenvolupament. c) Analitzar les relacions que hi ha entre els diferents agents i com afecten el desenvolupament de la xiqueta. d) Debatre propostes i actuacions per a minimitzar o potenciar l’impacte de determinats agents en el desenvolupament de la xiqueta.
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El document és l'anex 7.1.a. de la práctica 3. Desenvolupament psicomotor de 3 a 6 anys.
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Interleaved.
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3. Aus der "Dialektik der Aufklärung"; Kapitel: "Juliette oder Aufklärung und Moral". Typoskript mit dem Titel "Aufklärung und Rigorismus", mit handschriftlichen Korrekturen, 52 Blatt (2 Exemplare); 4. Aus der "Dialektik der Aufklärung"; Kapitel: "Kulturindustrie". Typoskript mit dem Titel "Das Schema der Massenkultur":; 4a) Typoskript mit handschriftlichen Korrekturen, 67 Blatt; 4b) Typoskript mit eigenen Korrekturen, 106 Blatt; 5. - 110. Gedruckte und ungedruckte Aufzeichnungen und Entwürfe zur "Dialektik der Aufklärung: Sammlungen A, B, C, D, die teilweise identisch sind; 5. - 42. Sammlung A: "Aphorismen"; 5. "Zum Problem der Bedürfnisse". Typoskript, 5 Blatt; 6. "Mensch und Tier". Typoskript mit eigenen Korrekturen, 12 Blatt; 7. "Propaganda". Typoskript, 2 Blatt; 8. "Straftheorie". Typoskript mit eigenen Korrekturen, 3 Blatt; 9. "Dichtung und Moral". Typoskript mit eigenen Korrekturen, 5 Blatt; 10. "Zur Genese der Dummheit". Typoskript, 3 Blatt; 11. "Interesse am Körper". Typoskript mit eigenen Korrekturen, 6 Blatt; 12. "Philosophie und Arbeitsteilung". Typoskript, 3 Blatt; 13. "Widersprüche". Typoskript, 4 Blatt; 14. "Geschichte der amerikanischen Arbeiterschaft". Typoskript, 1 Blatt; 15. "Feind". Typoskript, 2 Blatt; 16. "Gezeichnet". Typoskript mit eigenen Korrekturen, 2 Blatt; 17. "Erkenntnis und Sprache". Typoskript, 1 Blatt; 18. "Unmöglichkeit der Dichtung". Typoskript, 1 Blatt; 19. "Erbsünde und Kopula". Typoskript, 2 Blatt; 20. "Die Einseitigkeit der Negativität". Typoskript, 2 Blatt [= "Für Voltaire" in der "Dialektik der Aufklärung"]; 21. "Klassifikation". Typoskript mit eigenen Ergänzungen, 1 Blatt; 22. "Jüdischer Charakter". Typoskript mit eigenen Korrekturen, 1 Blatt; 23. "Lawine". Typoskript mit eigenen Korrekturen, 2 Blatt; 24. "Solidarität". Typoskript mit eigenen Korrekturen, 2 Blatt; 25. "Bewußtsein". Typoskript, 1 Blatt; 26. "Gegen Bescheidwissen". Typoskript, 1 Blatt; 27. "Der Gedanke". Typoskript, 1 Blatt; 28. "Quand-même". Typoskript, 2 Blatt; 29. "Leeres Erschrecken". Typoskript mit eigenen Korrekturen, 2 Blatt; 30. "Haupt- und Nebensatz". Typoskript, 3 Blatt; 31. "Verwandlung der Idee in Herrschaft". Typoskript mit eigenen Korrekturen, 5 Blatt; 32. "Isolierung durch Verkehr". Typoskript, 1 Blatt; 33. "Kampf und Gewaltlosigkeit". Typoskript, 6 Blatt; 34. "Zwei Welten". Typoskript, 2 Blatt; 35. "Zur Theorie der Gespenster". Typoskript, 1 Blatt; 36. "Notiz" [= "Umschlag der idealistischen Dialektik"]. Typoskript, 1 Blatt; 37. "Massengesellschaft". Typoskript, 1 Blatt; 38. "Tierpsychologie". Typoskript, 1 Blatt; 39. "Denkmale der Humanität". Typoskript mit eigenen Korrekturen, 1 Blatt; 40. "Physiognomik". Typoskript mit eigenen Korrekturen, 1 Blatt; 41. "Die Rackets und der Geist". Typoskript mit eigenen Korrekturen, 7 Blatt; 42. "Altmodisches Problem". Typoskript mit eigenen Korrekturen, 2 Blatt;
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The absorption spectra of DPH at fixed concentration do not change with water content in organic solvents. It exhibits monomer bands, such as those obtained in ethanol. The absorption did not change for solutions up to 54 and 46% of water in ethanol and DMSO, respectively, for [DPH] = 5.0 × 10-6 mol L-1 at 30 °C. However, at the same experimental conditions, a gradual sharp decay of the DPH fluorescence is observed. It is proposed that water molecules below these water concentration limits act as quenchers of the excited states of DPH. Stern-Volmer quenching constants by intensities measurements are 7.4 × 10-2 (water/ethanol) and 2.6 × 10-2 L mol-1 (water/DMSO). DPH lifetime measurements in the absence and presence of water resulted in 7.1 × 10-2 L mol-1 in water/ethanol, which pointed out that the process is a dynamic quenching by water molecules. For experiments using DPH as probe, this process can affect data, leading to misunderstanding interpretation.
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In the title compound, C(22)H(14)N(2)O(2), the five rings of the molecule are not coplanar. There is a significant twist between the four fused rings, which have a slightly arched conformation, and the pendant aromatic ring, as seen in the dihedral angle of 13.16 (8)degrees between the anthraquinonic ring system and the pendant aromatic ring plane.