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1	Synthesis of Hetero-chitooligosaccharides Issaree, Arisara January 2008 (has links) Chitooligosaccharides are composed of linear β-(1→4)-linked 2-acetamido-2-deoxy-β-D-glucopyranose (GlcNAc) and/or 2-amino-2-deoxy-β-D-glucopyranose (GlcN). They are of interest due to their remarkable biological properties including antibacterial, antitumor, antifungal and elicitor activities. They can be obtained from the aminoglucan chitosan by chemical or enzymatic degradation which obviously affords rather heterogenous mixtures. On the other hand, chemical synthesis provides pure compounds with defined sequences of GlcNAc and GlcN monomers. The synthesis of homo- and hetero-chitobioses and hetero-chitotetraoses is described in this thesis. Dimethylmaleoyl and phthaloyl groups were used for protection of the amines. The donor was activated as the trichloroacetimidate in order to form the β-linkages. Glycosylation in the presence of trimethylsilyl trifluoromethanesulfonate, followed by N- and O-deprotection furnished chitobioses and chitotetraoses in good yields. / Chitooligosacchride bestehen aus linear β-(1→4)-verknüpften 2-acetamido-2-deoxy-β-D-glucopyranose (GlcNAc) and/or 2-amino-2-deoxy-β-D-glucopyranose (GlcN) Einheiten. Sie beanspruchen aufgrund ihrer bemerkenswerten biologischen Eigenschaften – u.a. antibakterielle, antitumor, antimykotische und Elicitor Aktivität - grosses Interesse. Sie sind durch chemischen oder enzymatischen Abbau von Chitosan zugänglich, wobei diese Methoden unausweichlich zu komplexen, sehr heterogenen Mischungen von Chiooligosacchariden führen. Chemische Synthesen von Chitooligosacchariden mit definierter Sequenz von GlcNAc und GlcN Einheiten sind daher von erheblichem Interesse. In der vorliegenden Arbeit werden Synthesen von partiell acetylierten Chitobiosen und –tetraosen beschrieben. Die Aminogruppen wurden als N-Dimethylmaleoyl- bzw. Phthaloylimide geschützt. Die Donoren wurden als Trichloacetimidate aktiviert, wobei aufgrund von Nachbargruppeneffekten ausschliesslich die β-Glycoside entstehen. Die Trimethylsilyltrifluoromethansulfonat-promovierte Glycosidierung geeigneter Akzeptoren lieferte schliesslich die Chitobiosen und die Chitotetraosen in guten Ausbeuten. Kohlenhydrate Chitooligosaccharide Glycosylierung Synthesemethoden Trichloracetimidate Carbohydrates Chitooligosaccharides Glycosylation Synthetic methods Trichloroacetimidates Chemistry and allied sciences
2	Protein sorting and cell surface polarity in yeast / Proteinsortierung und Zelloberflächenpolarität in Hefe Proszynski, Tomasz 14 October 2005 (has links) (PDF) The studies presented here were focused on the understanding of the principles for protein sorting from the Golgi to the cell surface. As a marker protein we used Fus1p, a type I plasma membrane protein that is O-glycosylated on the extracellular domain and plays a role in cell fusion during yeast mating. Additionally, we analyzed mechanisms responsible for asymmetric distribution of Fus1p in mating cells. We demonstrated that the glycans attached to the protein act as a sorting determinant for protein transport to the cell surface. In cells lacking PMT4, encoding a mannosyltransferase involved in the initial step of O-glycosylation, Fus1p was not glycosylated and accumulated in late Golgi structures. A similar defect in exocytosis was observed when a Fus1p mutant lacking the O-glycosylated domain was expressed in wild-type cells, however, the cell surface delivery could be rescued if the 33 amino acid portion of the Fus1p ectodomain, containing 15 potentially glycosylated sites was added to the protein. It was previously well documented in epithelial cells that different types of protein glycosylation and association with lipid rafts play a role of determinants for protein delivery to the apical plasma membrane. However, otherwise the machinery responsible for cargo sorting to the apical membrane is poorly understood. Our finding that also in yeast, protein glycosylation can function as a sorting determinant provides a new possibility to investigate underlying mechanisms... Hefe Polarität Sortierung Screen Glycosylierung Rafts Yeast Polarity Sorting Screen Glycosylation Rafts ddc:570 rvk:WE 5300 Glykosylierung Hefeartige Pilze Polarität Protein-Sortierung Zelloberfläche
3	Stereoselektive Synthese von Sphingolipiden zur Inhibierung der Degranulation von Mastzellen Zankl, Claudia 07 August 2009 (has links) (PDF) Die Degranulation von Mastzellen soll durch Glycosphingolipide, welche mit der Zellmembran wechselwirken inhibiert werden. Der Sphingosingrundkörper wurde in zehn-stufigen Synthese ausgehend von N-Boc-Serin, aufgebaut. Die anschließende Glycosylierung erfolgte nach der Trichloracetimidatmethode in sehr guten Ausbeuten und stellte den Schlüsselschritt dar. Durch die Variation von unter Anderem der Amidseitenkette, der Glycosylkopfgruppe und des Sphingosingrundkörpers wurde eine Vielzahl an Derivaten für das Screening im Degranulationsassay bereitgestellt. / The present dissertation covers the synthesis of glycosphingolipids which interact with the cell membrane in order to inhibit the degranulation of mast cells. The sphingosin body was synthesized in ten steps starting from N-Boc-Serin. The key step, the glycosylation was achieved using the trichloracetimidat method. The variation of the amid sidechain, the gylcosyl headgroup and the sphingosin body created a number of derivatives that were tested in the degranulation assay. Sphingolipide Degranulation Mastzellen Glycosylierung Ceramide Trichloracetimidatmethode Lipid Rafts Sphingolipids Degranulation mast cells lipid rafts glycosylation ceramids trichloracetimidat ddc:540 rvk:VK 8520
4	Protein sorting and cell surface polarity in yeast Proszynski, Tomasz 30 August 2005 (has links) The studies presented here were focused on the understanding of the principles for protein sorting from the Golgi to the cell surface. As a marker protein we used Fus1p, a type I plasma membrane protein that is O-glycosylated on the extracellular domain and plays a role in cell fusion during yeast mating. Additionally, we analyzed mechanisms responsible for asymmetric distribution of Fus1p in mating cells. We demonstrated that the glycans attached to the protein act as a sorting determinant for protein transport to the cell surface. In cells lacking PMT4, encoding a mannosyltransferase involved in the initial step of O-glycosylation, Fus1p was not glycosylated and accumulated in late Golgi structures. A similar defect in exocytosis was observed when a Fus1p mutant lacking the O-glycosylated domain was expressed in wild-type cells, however, the cell surface delivery could be rescued if the 33 amino acid portion of the Fus1p ectodomain, containing 15 potentially glycosylated sites was added to the protein. It was previously well documented in epithelial cells that different types of protein glycosylation and association with lipid rafts play a role of determinants for protein delivery to the apical plasma membrane. However, otherwise the machinery responsible for cargo sorting to the apical membrane is poorly understood. Our finding that also in yeast, protein glycosylation can function as a sorting determinant provides a new possibility to investigate underlying mechanisms... info:eu-repo/classification/ddc/570 ddc:570
5	Stereoselektive Synthese von Sphingolipiden zur Inhibierung der Degranulation von Mastzellen Zankl, Claudia 06 July 2009 (has links) Die Degranulation von Mastzellen soll durch Glycosphingolipide, welche mit der Zellmembran wechselwirken inhibiert werden. Der Sphingosingrundkörper wurde in zehn-stufigen Synthese ausgehend von N-Boc-Serin, aufgebaut. Die anschließende Glycosylierung erfolgte nach der Trichloracetimidatmethode in sehr guten Ausbeuten und stellte den Schlüsselschritt dar. Durch die Variation von unter Anderem der Amidseitenkette, der Glycosylkopfgruppe und des Sphingosingrundkörpers wurde eine Vielzahl an Derivaten für das Screening im Degranulationsassay bereitgestellt. / The present dissertation covers the synthesis of glycosphingolipids which interact with the cell membrane in order to inhibit the degranulation of mast cells. The sphingosin body was synthesized in ten steps starting from N-Boc-Serin. The key step, the glycosylation was achieved using the trichloracetimidat method. The variation of the amid sidechain, the gylcosyl headgroup and the sphingosin body created a number of derivatives that were tested in the degranulation assay. info:eu-repo/classification/ddc/540 ddc:540
6	Structural characterization of the lysosomal 66.3 kDa protein and of the DNA repair enzyme Mth0212 by means of X-ray crystallography / Strukturelle Charakterisierung des lysosomalen 66.3 kDa Proteins und des DNA-Reparaturenzyms Mth0212 mittels Röntgenkristallographie Lakomek, Kristina 28 April 2009 (has links) No description available. 570 Biowissenschaften, Biologie Mathematics and Computer Science 66.3 kDa Protein lysosomale Proteine Glycosylierung N-terminal nucleophile Hydrolasen Autoproteolytische Aktivierung Schwefel-SAD DNA-Schaden DNA-Reparatur ExoIII-Homolog 2`-Desoxyuridin Kristallstruktur Röntgenkristallographie 66.3 kDa protein lysosomal protein glycosylation N-terminal nucleophile hydrolase autoproteolytic activation sulfur SAD DNA damage DNA repair ExoIII homolog 2`-deoxyuridine crystal structure X-ray crystallography 42.13 WF 200: Molekularbiologie

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