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31.
Sabine Lhernould Yannis Karamanos Patrice Lerouge Henri Morvan 《Glycoconjugate journal》1995,12(1):94-98
The peptide-N
4-(N-acetylglucosaminyl) asparagine amidase (PNGase Se) earlier described [Lhernould S., Karamanos Y., Bourgerie S., Strecker G., Julien R., Morvan H. (1992)Glycoconjugate J
9:191–97] was partially purified from culturedSilene alba cells using affinity chromatography. The enzyme is active between pH 3.0 and 6.5, and is stable in the presence of moderate concentrations of several other protein unfolding chemicals, but is readily inactivated by SDS. Although the enzyme cleaves the carbohydrate from a variety of animal and plant glycopeptides, it does not hydrolyse the carbohydrate from most of the corresponding unfolded glycoproteins in otherwise comparable conditions. The substrate specificity of this plant PNGase supports the hypothesis that this enzyme could be at the origin of the production of unconjugated N-glycans in a suspension medium of culturedSilene alba cells.Abbreviations GlcNAc
N-acetylglucosamine
- PNGase
peptide-N
4-(N-acetylglucosaminyl) asparagine amidase
- BSA
bovine serum albumin
- SDS-PAGE
sodium dodecyl sulfate-polyacrylamide gel electrophoresis
- TLC
thin layer chromatography
- HPAEC-PAD
High pH anion exchange chromatography-pulsed amperometric detection 相似文献
32.
Sabine Castano Bernard Desbat Isabelle Cornut Philippe Méléard Jean Dufourcq 《Letters in Peptide Science》1997,4(4-6):195-200
De novo designed extremely simplified amphipathic basicLeuiLysj (i = 2j) peptides of 8, 9 and 15residues were synthesized to clarify the mechanism of action of naturalcytotoxic and hemolytic small proteins or peptides. They proved to havestrong hemolytic activity towards human erythrocytes which increases withpeptide length. These peptides are highly surface active and form stablepeptidic films at the air/water interface. The sensitive and efficient FTIRmodulated polarization technique (PMIRRAS) allows one to obtain in situstructural and orientational information about the peptides at theinterface. A transition of secondary structure is observed: the shorterpeptides (8 and 9 residues) adopt -sheet structures while the longerone (15 residues) is folded into an -helix. In both cases, the peptideslie with the axis parallel to the interface. Their insertion into adimyristoylphosphatidylcholine monolayer can be followed from the increasein the surface and/or pressure of the films. In the mixed films, thepeptides adopt the same structure and orientation as observed at theair/water interface. Therefore, among the same series of peptides, atransition from -sheet to -helix occurs when the length increases(roughly >10 aa), but despite this drastic change both types ofstructures result in strongly hemolytic peptides. 相似文献
33.
34.
Klaus Kayser Sabine André Gerhard Böhm Sonia Donaldo-Jacinto Peter Fritz Herbert Kaltner Gian Kayser Wolf-Peter Kunze Andreas Nehrlich Fu-Yue Zeng Hans-Joachim Gabius 《Development genes and evolution》1995,204(5):344-349
Protein-carbohydrate interactions are supposed to play key roles in the mechanisms of cell adhesion, biosignalling and intracellular routing, warranting the analysis of the developmental course of expression of epitopes of this system. Thus, a panel of carrier-immobilized carbohydrate ligands was used as probes, namely lactose,N-acetylgalactosamine,N-acetylglucosamine, mannose, fucose and maltose. Additionally, an antibody to an endogenous -galactoside-binding lectin (anti-galectin-1), the biotinylated lectin and two further human lectins, namely the macrophage migration inhibitory factor-binding sarcolectin and serum amyloid P component (SAP) that displays selectivity for sulphated sugars and mannose-6-phosphate, were included. They enabled us to assess the extent of the presence of respective binding sites in fixed sections from human lungs (pulmonary epithelial cells), livers (hepatocytes) and hearts (myocard cells) of 10–50 weeks gestation. Invariably, specific binding was detected in the three organ types, at least in certain stages. In most of the cases, the intensity of staining exhibited developmental regulation. The apparent patterns reveal similarities between the different cell types, as seen with immobilizedN-acetylglucosamine as well as with labelled galectin-1 and sarcolectin. However, drastic differences among such patterns with nearly opposite developmental courses do also occur, as detected for carrier-attached mannose and maltose residues. These results point to a potential importance for the detected glycohistochemical features in human development and substantiate the possibility of differential regulation of the presence of binding sites for distinct sugars within a certain organ and between the individual cell types of the monitored organs. 相似文献
35.
36.
In-situ gelation of semidilute xanthan solutions with trivalent chromium, aluminum or iron ions was studied by rheology and UV-spectroscopy. Measurements of the elastic modulus of xanthan gel cylinders prepared by dialysis against the complexing ion at pH values from 2 to 6 indicate that monomeric species of the ion are ineffective, whereas dimeric or higher oligomeric species are effective in crosslinking the polysaccharide. When chromium was used as the crosslinking species, the dependence of the gelation rate on the ionic concentration followed a power law with a coefficient of 1·7. The gelation time and the gelation rate were found to extrapolate to zero at 1 m
Cr for 2·5 mg/ml xanthan. The limiting concentration of xanthan needed for gelation with 5 m
Cr(III) at 20°C was estimated as 0·35 mg/ml. This critical xanthan concentration is close to the overlap concentration c* estimated from the experimentally determined intrinsic viscosity [η] using c* = 1·4/[η]. An apparent activation energy for crosslinking of xanthan was calculated as Ea = 42 kJ/mol and Ea = 108 kJ/mol for Cr and Al ions, respectively. The fractal dimensionality of xanthan-Cr at the sol-gel transition was estimated as 1·3 applying the Chambon-Winter criterion for gelation, thus indicating that this gelation criterion is applicable also to stiff-chain polysaccharides such as xanthan. 相似文献
37.
38.
The DNase I sensitivity of three different chromatin regions in mouse testicular cells was analysed by in situ nick translation with biotin-dUTP combined with various counterstaining techniques. The regions were: (i) the constitutive centromeric heterochromatin, (ii) an interstitial C-band positive insertion on chromosome 1, Is(HSR1;C5)1Lub, and (iii) the chromatin containing rDNA (designated nucleolar chromatin herein). Incorporated biotin was detected either by the horseradish peroxidase reaction with diaminobenzidine (DAB) or the alkaline phosphatase reaction with fast red. The latter resulted in a water insoluble red precipitate, which was easily removable by any organic solution thus allowing the application of various counterstaining protocols. DNase I sensitivity of the three chromatin regions was screened in different cell types of the mouse testis. The interstitial Is(HSR) region was highly DNase I sensitive when it was recognizable by strong mithramycin fluorescence. The centromeric heterochromatin was DNase I resistant when it was compacted into microscopically visible chromosomal structures (mitosis, pachytene, metaphase I and II). In interphase nuclei from Sertoli cells and spermatogonia it became highly DNase I sensitive. In round spermatids it displayed medium DNase I sensitivity. Nucleolar chromatin was not labelled by in situ nick translation when silver staining demonstrated strong protein production. Sperm cells were highly DNase I sensitive from stages 11 to 15, but resistant as mature spermatozoa. 相似文献
39.
Summary The rate of spontaneous chromosomal aberrations in fibroblasts of a patient with Fanconi's anemia was slightly reduced after cocultivation with Chinese hamster ovary (CHO) cells. However, after mitomycin C treatment, a significant reduction of induced chromosomal damage was found in the FA cells while a significant increase was observed in the CHO cells. This antagonistic effect could be attributed to some diffusible agent(s). The results are discussed with respect to the underlying mechanism of the disease. 相似文献
40.
Zusammenfassung Der Waldrapp verfügt als soziale Vogelart über Verhaltensweisen des Gruppen- wie Paarkontaktes, die durch Veränderung von Körperumriß und Färbung unbefiederter Hautstellen verstärkt werden können: Grüßen, Imponieren, Aggressivverhalten (auch bei Nestlingen), Beschwichtigen, soziale Körperpflege, Kopula, Nestbau-Verhalten, Paarsitzen. Für das Zusammenspiel der Kolonie wichtig sind Grüßen, verschiedene Formen des Imponierens und ritualisierte Aggressionshandlungen. Das Fortpflanzungsgeschehen synchronisieren soziale Gefiederpflege, Kopulationen (bzw. Scheinkopulae) und Nestbauhandlungen. Das Paarsitzen, besonders deutlich außerhalb der Brutperiode, zeigt vermutlich Monogamie an.Das Lautrepertoire, eintönig für das menschliche Ohr, ist individuell variabel.Eine Besonderheit der Waldrappe ist auch die Nestlings-Aggressivität. Nestgeschwister trachten, einander durch Schnabelhiebe in eine Beschwichtigungshaltung zu drängen und so am Betteln zu hindern. Das Verhalten erlischt bei Erreichen eines Gewichtes von ca. 800 g, zugleich mit dem Abflachen der Wachstumskurve. Da Waldrappe ab dem ersten Ei brüten, überleben untergewichtige Letztgeschlüpfte (Nesthäkchen) bei ausreichendem Nahrungsangebot aufgrund ihrer länger anhaltenden Aggressivität.
Social behaviour of the Bald IbisGeronticus eremita — observations at the Alpenzoo, Innsbruck
Summary As a social bird the Bald Ibis shows behaviour patterns for group contact as well as for pair contact: greeting, display, aggressive behaviour of adults and sibling competition, appeasement behaviour, social preening, nesting behaviour, and Paarsitzen (spatial bond). Some of them may be reinforced by changing body-shape and colour of unfeathered skin. Greeting, some forms of display and ritualized aggressions are important for normal intraspecific interactions. Social preening, copulations (false copulae also) and nesting behaviour do not only stimulate the partner, they also synchronize activity within a colony. Paarsitzen might indicate longer lasting monogamy. The vocal inventory is rather uniform, but some calls may vary individually. — The Bald Ibis shows a strong sibling competition. Siblings force to prevent each other to gape by violent pecking and thus releasing appeasement behaviour. Sibling competition stops with about 800 g at the end of the period of rapid body growth. As the Bald Ibis is breeding with the first egg, this behaviour may allow survival of the runt because of its longer lasting aggressivity when there is sufficient food supply.相似文献