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SINGH, MEENAKSHI. "Synthesis of Group B Streptococcus tipe II (GBSII) Oligosaccharide of Vaccine Development." Doctoral thesis, Università degli Studi di Milano, 2019. http://hdl.handle.net/2434/680023.
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Carbohydrates are among the most abundant molecules found on the cell surfaces of bacteria, parasites, and viruses. Apart from the conventional roles of carbohydrates as energy sources and structural polymers, carbohydrates are also associated with cancer metastasis, protein stabilization, pathogen infection and the immune response. Cells of our body have sensors made out of carbohydrates on outer surface of plasma membrane and acts as sensors and can detect many kinds of stimuli, and can signal the immune system to respond. Carbohydrate-protein molecular recognition processes have pivotal roles in infections and in immune response to pathogens. To date, several vaccines based on isolated capsular polysaccharides (CPSs) are marketed against infectious diseases. However, the use of isolated capsular polysaccharide poses several limitations, as natural sources are generally limited and the isolation is very challenging. Additionally, the isolated polysaccharides are heterogeneous and often contains impurities. Furthermore, limited protection of certain CPS antigens impairs the efficiency of vaccines. To overcome limitations associated with isolated polysaccharides, synthetic oligosaccharides present an effective alternative with great potential to understand glycan immunology and rationally design effective antigens. Consequently, characterization and reconstruction of carbohydrate epitopes with authentic composition has become one of the major target in glycoscience. To this end, strategies are needed to facilitate the streamlined design and generation of these antigens.
This thesis concerns the development of an effective synthetic strategy to obtain Group B Streptococcus (GBS) type II oligosaccharide for vaccine development. GBS, a Gram-positive bacterium, inhabits the intestinal and genitourinary tract of 10‐30% of humans. GBS is one of the primary causes of bacterial infections among neonates and pregnant women, resulting in many severe diseases such as sepsis, meningitis, abortion, and so on. Type II GBS is one of the predominant GBS serotypes and is associated with about 15% of the invasive infections in adults and infants; therefore, represents an important human pathogen. The development of effective preventive vaccine against GBS is much needed to help pregnant women protect their newborns. This thesis describes the effective synthetic strategy to synthesize GBS type II oligosaccharide to be applied for vaccine development.
Herein, we present a new and convenient synthesis of the repeating unit of GBS type II capsular polysaccharide. The structure of GBS type II was elucidated in 1983 and the repeating unit of GBS type II is a heptasaccharide composed of α-Neu5Ac (2-3)-ß-D-Gal-(1-4)- ß-D-GlcNAc-(1-3)-[-ß-D-Gal-(1-6)]-ß-D-Gal-(1-4)-ß-D-Gal-(1-3)-ß-D-Glc. The presented synthetic strategy is based on the five subcomponents derived from the retro synthetic analysis. Suitably protected lactosamine and lactose derivatives are pivotal building blocks in our synthesis and both disaccharide fragments have been achieved from the cheap and readily available lactose. Having started from two disaccharides saves the efforts of glycosylation and reduces the number of synthetic steps. The building blocks have been obtained in good overall yield following the optimized synthetic approach. The synthesis of backbone linear chain trisaccharide [ß-D-Gal-(1-4)-ß-D-Gal-(1-3)-ß-D-Glc] and pentasaccharide [ß-D-Gal-(1-4)-ß-D-GlcNAc-(1-3)-ß-D-Gal-(1-4)-ß-D-Gal-(1-3)-ß-D-Glc] has been achieved in excellent yield (~80% yield). The final steps of the synthesis comprise- the incorporation of ß-D-Gal unit into the linear chain pentasaccharide (currently ongoing) followed by the enzymatic introduction of sialic acid (NeuNAc unit) and subsequent deprotection to yield the repeating unit of GBS type II capsular polysaccharide.
To conclude, in this thesis we present an efficient and easy handling synthetic approach to the heptasaccharide repeating unit of GBS type II. Readily available and cheap dairy side-product lactose has been used as a key structure in the presented scheme, allowing the efficient synthesis of the pentasaccharide backbone of the target compound. The synthetic GBS II fragments will be used for glycan array and structural studies and immunochemical characterization with specific monoclonal antibodies.
This thesis comprises of four main chapters and the experimental section containing the methods and synthetic procedures for the discussed schemes. Chapter one is a general introduction and deals with the necessity and the social importance of the described project.
Chapter two of the thesis outlines the scientific background and pathogenesis of GBS, carbohydrates and their biological importance, and general introduction of vaccines and how the carbohydrates can be used as a suitable vaccine candidate. Chapter two establishes the importance of synthetic carbohydrates and how the synthetic carbohydrates can be used to develop suitable effective vaccines against GBS diseases.
Chapter three of the thesis contains the general introduction and structural features of GBS II CPS and the retrosynthetic analysis of GBS II CPS to identify the building blocks for the synthesis of GBS CPS II.
Chapter four of the thesis summarizes the synthetic strategies and results to achieve the building blocks described in chapter three and the recombination of fragments to achieve the final molecule GBS II CPS repeating unit.
The last part of the thesis will consists of the experimental methods and synthetic procedures to achieve the proposed molecule along with the characterization data.
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Fusari, M. M. "SYNTHESIS OF FRAGMENTS OF SALMONELLA TYPHI CAPSULAR POLYSACCHARIDE AND THEIR ZWITTERIONIC ANALOGUES." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/243479.
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Polysaccharide antigens are T cell-independent antigens, and do not induce immune B cell memory. Consequently, vaccines based on polysaccharides have limited clinical usefulness and induce short-lasting antibody responses in adults. Their immunogenicity can be enhanced by conjugation to an immunogenic carrier protein, generating T cell-dependent glycoconjugate antigens able to induce immunological memory. However, these glycoconjugates suffer from some problems. Recent investigations have found a group of structurally distinct bacterial polysaccharides able to activate T cells in vivo and in vitro. They present a zwitterionic charge motif distributed along the chain and, for this reason, they are called zwitterionic polysaccharides (ZPSs). This zwitterionic charge motif is believed to be responsible for their particular immunological behavior. The integrity of the zwitterionic motif is essential for the biological activity of ZPS. However, it must be clarified if the introduction of the zwitterionic motif into a naturally non-zwitterionic polysaccharide confers to the resulting ZPS the ability to activate T cells without protein conjugation. To this end, zwitterionic oligomers must be obtained by chemical modification of fully synthetic, non-zwitterionic polysaccharide fragments. With these compounds in hand it would be possible to correlate structural and conformational properties of the ZPS with their biological activity, in terms of charge pattern and minimum molecular weight required for immunogenicity. For this purpose the capsular polysaccharide (CPS) of Salmonella typhi was chosen as a suitable model for our investigation. S. typhi is an encapsulated Gram-negative bacterium that causes typhoid fever. Its CPS, commonly named Vi antigen, is an anionic polymer composed of alpha-(1-4)-linked N-acetylgalactosaminuronic acid repeating units predominantly O-acetylated at position 3. Recent studies indicated the importance of the acetylation for the immunogenicity. The structure of the Vi antigen makes it an ideal candidate for our investigation, since its fragments can be easily converted into zwitterionic derivatives by formal N-deacetylation, without introducing huge structural modifications.
We designed a flexible synthetic strategy in order to obtain, from common building blocks, two distinct series of oligomers: the ones corresponding to the natural structure and their zwitterionic derivatives. Moreover, the role of 3-O-acetylation will be investigated by the synthesis of both fully 3-O-acetylated and fully 3-non-O-acetylated oligosaccharides. We selected N-phenyltrifluoroacetimidate moieties as the best leaving group in the glycosyl donors. Moreover, all the oligomers were endowed with a suitable linker at the anomeric position of the reducing end in order to facilitate subsequent conjugation to multivalent scaffolds.
In the first part of the work the synthesis of oligomers non acetylated at position 3 is described. The glycosyl donor and acceptor were obtained from commercially available D-galactosamine hydrochloride. Their glycosylation was performed by a slow addition of a diluted solution of the Lewis acid via a syringe pump, and complete alpha stereoselectivity was obtained. We also successfully applied a more efficient elongation strategy based on disaccharide donors to the synthesis of the Vi trisaccharide and its zwitterionic derivative.
Evaluation of the biological behavior of the target compounds was also performed by ELISA competitive assay.
The second part of the work was focused on the synthesis of oligomers acetylated at C-3. In particular, a different approach based on pre-oxidized galacturonate building blocks obtained via inversion of C-4 configuration of commercially available D-glucosamine hydrochloride is described.
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Ruffing, Anne M. "Metabolic engineering and omics analysis of Agrobacterium sp. ATCC 31749 for oligosaccharide synthesis." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/39507.
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Oligosaccharides are important biomolecules that are targets and also components of many medical treatments, including treatments for cancer, HIV, and inflammation. While the demand for medically-relevant oligosaccharides is increasing, these compounds have proven difficult to synthesize. Whole-cell oligosaccharide synthesis is a promising method that requires relatively inexpensive substrates and can complete the synthesis in just one step. However, whole-cell oligosaccharide synthesis employing common microorganisms like E. coli have been plagued by low yields. This dissertation investigates an alternative microorganism for oligosaccharide production: Agrobacterium sp. ATCC 31749. This Agrobacterium strain produces high levels of curdlan polysaccharide, demonstrating its natural ability to produce the sugar nucleotide precursor for oligosaccharide production. The two main objectives of this dissertation are 1) to develop biocatalysts for oligosaccharide synthesis by engineering ATCC 31749 and 2) to determine what factors affect poly- and oligosaccharide production in this Agrobacterium strain. ATCC 31749 was engineered to produce two oligosaccharides of medical importance: N-acetyllactosamine and galactose-α 1,3-lactose. Oligosaccharide production in the biocatalyst was further improved with additional metabolic engineering. Substrate uptake was increased through expression of a lactose permease, and availability of the sugar nucleotide substrate improved with gene knockout of the curdlan synthase gene. Both of these engineering efforts led to increased oligosaccharide synthesis in the Agrobacterium biocatalyst. Overall, the engineered Agrobacterium strains synthesized gram-scale quantities of the oligosaccharide products in just one step and requiring only a few inexpensive substrates and cofactors. Additional improvement of the oligosaccharide-producing biocatalysts required further investigation of the factors influencing poly- and oligosaccharide production in ATCC 31749. In this dissertation, several environmental and intracellular factors are identified that affect both oligosaccharide and curdlan production. Sucrose was the preferred carbon source for oligosaccharide synthesis, and the addition of citrate to the synthesis reaction led to significant improvement in oligosaccharide production. To identify the genetic factors and possible mechanisms regulating curdlan production, the genome of ATCC 31749 was sequenced. The genome sequence was utilized for transcriptome analysis of ATCC 31749. In the transcriptome analysis, genes significantly up- and down-regulated during curdlan production were identified. Subsequent gene knockout experiments showed several factors to be important for curdlan synthesis, namely the nitrogen signaling cascade, polyphosphate, and the GTP-derived second messengers (p)ppGpp and c-di-GMP. In addition to the development of biocatalysts for oligosaccharide production, this investigation provides insight into the complex mechanisms regulating exopolysaccharide synthesis.
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Watts, Christopher Rohan. "Synthesis of complex oligosaccharide." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624487.
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Le, Guen Yann. "Synthèse de fragments diversement acétylés des polysaccharides spécifiques des bactéries Shigella flexneri type I." Thesis, Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCB143.
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Shigella flexneri est une entérobactérie Gram négatif responsable de la forme endémique de la shigellose, l’une des quatre causes majeures d’infection diarrhéique chez les jeunes enfants. La cible majeure de la réponse immunitaire lors d’une infection naturelle est le polysaccharide de surface (PS). Chez S. flexneri 1b, l’un des sérotypes prévalents dans les pays en voie de développement, le PS est défini par le pentasaccharide ramifié α-L-rhamnopyranosyl-(1→2)-α-L-rhamnopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→3)-[α-D-glucopyranosyl-(1→4)]-2-acetamido-2-deoxy-β-D-glucopyranoside [I] di-O-acétylé. Ces travaux s’intègrent dans un projet visant le développement d’un vaccin basé sur des sucres synthétiques à couverture large contre les infections par Shigella. Afin de concevoir des glycoconjugués efficaces et induisant une bonne réponse immunitaire chez les enfants, des synthèses multi-grammes des précurseurs mono- à pentasaccharidiques ont été optimisées permettant une stratégie par blocs en vue de l’obtention d’oligosaccharides de grande taille. Au cours de ces synthèses, l’obtention du trisaccharide ramifié C(E)D clé a nécessité de nombreuses optimisations, permettant la conception de synthons tri- à pentasaccharides. Un choix des groupements protecteurs orthogonaux nous a permis d’investiguer les différentes conditions de couplages nous donnant accès à 28 oligosaccharides déprotégés courts diversement acétylés. La validation de ces condensations avec des partenaires plus complexes a permis d’accéder à un large panel d’une cinquantaine d’oligosaccharides de di- à pentadécasaccharides sous leur forme libre, ou encore protégés avec divers degrés d’acétylation700,000 children die each year due to diarrheal diseases, making it the second cause of death among this population. Shigella flexneri is a Gram negative enterobacterium responsible of the endemic form of shigellosis in developing countries. The O-antigen part of the bacterial lipopolysaccharide is the major target of the immune system during natural infection. The O-antigen of S. flexeni 1b, one of the prevalent serotypes, is defined by a ramified pentasaccharide made of three L-rhamnose, one D-glucosamine and one D-glucose with two non-stoichiometric sites for acetylation (I). This work is part of the project aimed at the development of a synthetic carbohydrate-based vaccine against Shigella infections. In order to obtain suitable glyconjugates inducing a high level of protection especially in children, the synthesis of mono- to pentasaccharide precursors was optimized, allowing a convergent synthesis of oligosaccharides with different acetylation patterns. Optimization of the glycosylation conditions, acetylations and protecting group manipulations enable the access to fragments from di to pentadecasaccharides representing S. flexneri type I O-antigen
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Drouin, Ludovic. "New methodology for oligosaccharide synthesis." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444903.
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Belogi, Gianluca. "Boronate esters in oligosaccharide synthesis." Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367628.
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Patikis, Angela. "Enzymic studies of oligosaccharide synthesis." Thesis, University of Westminster, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319626.
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Davis, Nicola Jane. "Synthesis of sulphated oligosaccharides." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259866.
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Nilsson, Magnus. "Chemical synthesis of oligosaccharide bacterial antigens /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5738-6.pdf.
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Cancogni, D. "MICROFLUIDIC REACTOR TECHNOLOGY IN OLIGOSACCHARIDE SYNTHESIS." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/229555.
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Although carbohydrates offer new therapeutic opportunities in biomedical field, the industrial implementation of carbohydrate-based drugs is yet greatly thwarted by the difficulties and challenges inherent in oligosaccharide synthesis, especially for large scale preparation. Any tool or new technology enabling a cost-effective improvement of the lead generation process is therefore highly desirable in order to reduce the manufacturing costs of carbohydrate drugs. During last years, continuous-flow synthesis in microreactors has gained a great deal of attention featuring practical advantages such as high reproducibility, easy scalability and fast reaction optimization using small amounts of reagents or synthetic intermediates. This technique may therefore offer an effective support to make carbohydrates more attractive targets for drug discovery processes. In addition, also basic research in academia can benefit from microreactor technology as a tool to improve the organic synthesis of oligosaccharides. Here I report a systematic exploration of the glycosylation reaction, the most important and difficult transformation in oligosaccharide synthesis, carried out in microreactors under continuous-flow conditions. Various trichloroacetimidates and thioglycosides have been investigated as glycosyl donors in this study, using both primary and secondary glycosyl acceptors. Each microfluidic glycosylation has been compared with the same reaction performed under traditional conditions, in order to highlight advantages and drawbacks of microreactors technology. As a significant example of multistep continuous-flow synthesis, we also describe the preparation of a trisaccharide by means of two consecutive glycosylations performed in two interconnected microreactors. Furthermore I report preliminary study on the synthesis of glycosyl phosphodiester under microfluidic conditions for the preparation of short oligomers of Neisseria Meningitidis type X capsular polysaccharide fragments.
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Thomas, Baptiste. "Conception et synthèse d'hétéroglycoclusters pour l'immunothérapie anticancéreuse." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENV037/document.
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Le cancer est une cause majeure de mortalité dans le monde. Bien que les taux de décès aient fortement diminués grâce aux diagnostiques précoces et la mise au point de traitements multiples, les récidives sont fréquentes. Parmi les principaux traitements, la chimiothérapie présente une toxicité extrêmement élevée et la radiothérapie conduit souvent à la destruction de tissus sains, alors que des tumeurs errantes peuvent échapper à la chirurgie. L'immunothérapie offre une l'alternative particulièrement intéressante pour combattre le cancer. En particulier, le développement de vaccins thérapeutiques et/ou prophylactiques capables de traiter, et idéalement, protéger efficacement contre de tumeurs représente un objectif ambitieux. Notre équipe a décrit récemment une nouvelle génération de vaccins synthétiques qui incorporent dans la même molécule un cluster d'oligosaccharides (épitopes des cellules B), un peptide chimère (épitopes des cellules T) et un acide palmitique (adjuvant) lié à son extrémité N-terminale. Les études immunologiques ont révélé une régression tumorale et une augmentation spectaculaire du taux de survie chez la souris, sans administration d'adjuvants externes.Sur la base de ces travaux, notre objectif a été de développer une approche chimique qui permette d'accéder à des structures plus sophistiquées et plus immunogènes. Pour cela, nous avons mis au point des méthodologies de synthèse chimiosélectives telles que la ligation oxime (OL), la cycloaddition alcyne-azoture catalysée par le Cu(I) (CuAAc), le couplage thiol-chloroacétyle (TCC) et/ou le couplage thiol-ène (TEC) pour préparer des homoglycoclusters (4-, 16- ou 64-valent) ou d'hétéroglycocluster de combinaison variable (2+2, 3+1, 4+2, 8+8, 4x1 et 4x4) via différents types de liens chimiques (oxime, triazole, thioéther). Ces méthodes ont été appliquées à la synthèse de candidats vaccins portant les marqueurs osidiques Tn et/ou TF et un peptide immunostimulant. Des études biologiques avec des lectines bactériennes (LecB) ou végétale (UEA-I) ont été réalisées pour valoriser les composés glycosylés modèles (Fuc, Man, Gal) synthétisés au cours de cette thèse et ont permis de découvrir de ligands nanomolaires. Les études immunologiques actuellement en cours avec nos candidats vaccins permettront quant à elles de déterminer l'influence du linker, de la valence et de la composition en antigène sur la réponse immunitaire induiteCancer is a major cause of mortality worldwide. Even if the rate of deaths has decreased thanks to early diagnostics and the creation of a variety of treatments, reccurence happen frequently. Among the main treatments, chimiotherapy shows a very high toxicity and radiotherapy often leads to the destruction of healthy cells, while released tumors can be left around by surgery. Immunotherapy offers a very interesting alternative to fight cancer. The development of therapeutical and/or prophylactical vaccines, able to treat and protect against tumors, seems to be an ambitious goal. Our team has recently described a new generation of synthetical vaccines which involve in the same molecule an oligosaccharide cluster (B cells epitopes), a chimer peptide (T cells epitopes) and a palmitic acid (adjuvant), bound on its N-terminal end. Immunological studies have revealed a reduction of the tumor size and a spectacular increase of the survival rate on mice, without having to administrate any extern adjuvant. On the basis of these studies, our goal has been to develop a chemical approach which would give access to more sophisticated and more immunogenic structures. To do this, we have developed methodologies of chemoselective synthesis, such as oxime ligation, Cu(I) catalysed alkyne-azide cycloaddition, (CuAAc), the thiol-chloroacétyle (TCC) and/or the thiol-ène coupling (TEC), to prepare homoglycoclusters (4-, 16- or 64- valent) or heteroglycoclusters of variable combination (2+2, 3+1, 4+2, 4x1, 8+8, 4x4) via different kind of chemical links (oxime, triazole, thioéther). These methods have been applied to the synthesis of vaccine candidates having the same carbohydrate Tn and/or TF and an immunostimulating peptide. Some biological studies with bacterial (LecB) or vegetal (UEA-I) lectines have been realised to highlight the glycosylated compounds's templates (Fuc, Man, Gal) synthesized during this PhD and have revealed nanomolar ligands. The immunological studies currently in progress on our vaccine candidates will help to understand the influence of the linker, the valence and the antigen composition on the immune response created
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Greenwell, David Robert. "Template directed synthesis of oligosaccharides." Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275698.
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Horrobin, Tina M. "The chemoenzymatic synthesis of oligosaccharides." Thesis, University of Warwick, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307318.
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Wilstermann, Michael. "Synthesis of conformationally restricted oligosaccharides." Lund : Dept. of Organic Chemistry 2, Lund University, 1997. http://catalog.hathitrust.org/api/volumes/oclc/39751534.html.
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France, Robert. "An electrochemical approach to selective oligosaccharide synthesis." Thesis, University of Oxford, 2004. http://ora.ox.ac.uk/objects/uuid:d46602e8-b05a-4791-8a31-ac92a42fb93d.
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This thesis describes investigations into the use of electrochemical oxidation as a method for the activation of glycosyl donors, and in particular the application of this technique to the selective activation of one electrochemically active glycoside over another. The synthesis of twenty eight electrochemically active monosaccharide donors, including thio-, seleno- and O-glycosides with varying protecting group patterns and anomeric substituents is described, together with the synthesis of three electrochemically active monosaccharides with the potential to act as both glycosyl donors and glycosyl acceptors. The electrochemical analysis of these monosaccharides is reported and gives a detailed insight into the effect of various factors on the oxidation potentials of the monosaccharide donors and allows some general conclusions to be drawn. In addition the analysis of six monosaccharides by cyclic voltammetry at scan rates of up to 25 000 Vs-1 allows their homogenous kinetics to be outrun and formal oxidation potentials obtained. Investigations into selective electrochemical glycosylations are reported, and the applicability of the analytical electrochemical studies to synthetic electrochemical reactions is demonstrated. Selective glycosylations are possible with selenoglycoside donors and either thio- or O-glycoside acceptors to give disaccharides. However the selective activation of selenoglycosides over thioglycosides is shown to be complicated by some underlying pathway for indiscriminate activation of both donor and acceptor. In contrast the use of an O-glycoside donor experiences no such problems. More detailed work on the underlying problems experienced with the thioglycoside acceptor was conducted, and the results are reported here. Investigations into electrochemical activation of the disaccharides are discussed, and the thioglycoside is shown to be easily activated to give a trisaccharide. At the time of writing this is believed to be the only electrochemically mediated trisaccharide synthesis reported in the literature. The O-glycoside however is shown to be inactive under the electrochemical oxidation conditions employed.
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Yao, Yanping. "Study on chemical synthesis in chitin oligosaccharide analogues β-1, 3-N-acetyl-glucosamine oligosaccharides and their induced resistance of plants to diseases." Paris 6, 2006. http://www.theses.fr/2006PA066589.
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Schmidt, Dirk. "Chemoenzymatische Synthese sialylierter Oligosaccharidstrukturen durch Transglycosylierung." [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=962775215.
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Qian, Xiangping. "Enzymatic and chemical synthesis of oligosaccharide analogs." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0013/NQ60015.pdf.
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Whitaker, Simon Richard. "Applications of Ionic Liquids to Oligosaccharide Synthesis." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.629002.
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The synthesis of a library of biologically relevant oligosaccharide fragments is proposed using ionic liquids as purification tags. Work to synthesise ,B(1-t3)-glucans as a model using this functionality has been considered and synthesis of a range of orthogonally protected glycosyl donors and glycosyl acceptors with ionic liquid purification tags has been achieved. Glycosylations using these building blocks resulting in ionically-tagged oligosaccharides have been performed and the results analysed herein. A continuation of previously published work using ionic liquids as mild room temperature glycosylation promoters is also reported: A variety of glycosyl donors were synthesised and tested with ionic liquids to determine reactivities of donors compatible with this methodology. Proposals to further the scope of this synthetic technique are also discussed.
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Franz, Andreas H. "Oligosaccharide mimics: Synthesis, characterization and biological properties." Scholarly Commons, 2000. https://scholarlycommons.pacific.edu/uop_etds/2752.
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In view of the significance of oligosaccharides in biological processes and the distinct disadvantage of easy metabolic degradation by glycosidases, a synthetic effort to prepare oligosaccharide mimics with enhanced metabolic stability was undertaken. This thesis introduces a new methodology for a high-yielding synthesis of mono- or oligosaccharidic glycals under non-solvolytic conditions. Lewis acid promoted glycal dimerization followed by introduction of a glycosyl cyanide functionality converted the compounds into possible anchors for pharmacophores. The experiments are discussed with respect to general applicability of the synthetic methods, stereoselectivity, and the biological properties of the compounds.
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Wright, Karen. "Synthesis of oligosaccharides affecting cell adhesion." Thesis, University College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267483.
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MacManus, D. A. "Enzymatic synthesis of glycosides and oligosaccharides." Thesis, University of Warwick, 1991. http://wrap.warwick.ac.uk/110506/.
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The β-D-galactosidase of Escherichia coli catalysed galactosyl transfer to a variety of acceptor substrates. Transfers to simple alcohols were followed by transfers to chiral alcohols, chiral diols (bearing primary and secondary hydroxyl groups) and to a me so- diol. In particular, the regio- and stereoselective aspects of the reactions were investigated. In general, transfer to primary hydroxyl groups was favoured over transfer to secondary hydroxyl groups, but little or no preference for the transfer to specific enantiomers in a racemic mixture was observed. The results for propane-1,2-diol and butane- 1,3-diol are interpreted in terms of the possible conformations which might be adopted at the active site of the enzyme. Transfer to cii-cyclohexa-3,5-diene- 1,2-diol gave rise to two diastereoisomers. During the early stages of the reaction, a diastereoisomeric excess of ca. 80% was observed; this was reduced to ca. 20% as the yields of product reached their maximum values. Assignment of the structures of the products was based on a combination of the techniques of nuclear Overhauser enhancement and molecular modelling. α-Galactosyl transfers to lactose and cellobiose using Mortierella vinacea a-D-galactosidase were also studied. In both cases, a single trisaccharide was isolated. Spectroscopic evidence indicated that a (1-6) linkages had been formed in both cases. An acrylamide/acrylic acid polymer intended for use in enzymatic oligosaccharide synthesis was developed. The polymer was high swelling so as to allow permeation by the enzyme and could be easily stored. An attempt to introduce chiral cavities specific for certain monosaccharides was made by substituting part of the acrylamide for a boronate-containing acrylamide and carrying out the polymerisation in the presence of the monosaccharide. The success of the imprinting procedure was measured by the ability of the polymer to separate the components of a racemic mixture of the monosaccharide. The application of such "molecular imprinting" as an aid to oligosaccharide synthesis is discussed.
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Baeschlin, Daniel Kaspar. "Butanediacetals in oligosaccharide synthesis : total synthesis of a GPI anchor." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621500.
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Pfister, Hélène. "Synthèse d'oligosaccharides représentatifs de l'antigène O de Shigella sonnei." Thesis, Paris 5, 2014. http://www.theses.fr/2014PA05P619.
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Avec 800 000 morts par année, les maladies diarrhéiques sont la seconde cause de mortalité chez les enfants de moins de cinq ans. La shigellose, causée par des bactéries Gram négatif appelées Shigella, est l’une des quatre grandes maladies entériques touchant cette population. L’infection naturelle protège contre la réinfection et la composante polysaccharidique du lipopolysaccharide bactérien est la principale cible de l’immunité humorale. Chez S. sonnei, espèce prévalente dans les pays en développement et développés, ce polysaccharide spécifique, à caractère zwitterionique, a pour unité répétitive un disaccharide composé de deux hexosamines rares : l’acide 2-acétamido-2-désoxy-L-altruronique (A) et le 2-acétamido-4-amino-2,4,6-tridésoxy-D-galactose (B, aussi appelé AAT) associés par des liens glycosidiques 1,2-trans (I). ->4-a-L-AltpNAcA-(1->3)-b-D-FucpNAc4N-(1-> (I). Ces travaux s’intègrent dans un programme visant le développement d’un vaccin issu de sucres de synthèse à couverture large contre les infections par Shigella. Le premier objectif de la stratégie développée contre les infections par S. sonnei est l’identification des épitopes saccharidiques, cibles des anticorps protecteurs. Dans ce but, nous avons entrepris la synthèse d’une diversité de fragments du polysaccharide d’intérêt. Des synthèses multi-grammes de précurseurs orthogonalement protégés des monosaccharides A et B ont été mises au point afin d’accéder aux intermédiaires donneurs et accepteurs impliqués dans les étapes de glycosylation. En particulier, deux voies originales d’accès au précurseur B ont été développées. D’autre part, l’optimisation des conditions de glycosylation et d’oxydation a conduit à un bloc disaccharidique AB compatible avec la synthèse d’oligosaccharides d’ordres supérieurs. Les synthons mono- et disaccharidiques identifiés ont été validés à travers l’obtention de quatre disaccharides portant ou non des modifications de la répartition des charges, de deux trisaccharides ainsi que d’un tétrasaccharide800,000 children die each year of diarrhoeal diseases, making it the second cause of death among children under five. Shigellosis, caused by a Gram negative bacterium, Shigella, is one of the four major forms of diarrhoeal diseases in this population. Natural infection protects against reinfection and the humoral response is primarily directed against the specific polysaccharide moiety of the bacterial lipopolysaccharide. S. sonnei, the prevalent species in developed and transitional countries, displays a zwitterionic polysaccharide, whose disaccharide repeating unit is made of two rare aminosugars: a 2-acetamido-2-deoxy-L-altruronic acid (A) and a 2-acetamido-4-amino-2,4,6-trideoxy-D-galactose (B, AAT) 1,2-trans linked to one another (I). ->4-a-L-AltpNAcA-(1->3)-b-D-FucpNAc4N-(1-> (I). This work is part of the program aimed at the development of a synthetic carbohydrate-based broad coverage vaccine against Shigella infections. In order to define the protective epitopes located on the O-specific polysaccharide of S. sonnei, we tackled the synthesis of fragments thereof. First, multigram-scale syntheses of orthogonally protected precursors to residues A and B were undertaken to access donor and acceptor intermediates in the glycosylation reactions. In particular, two original routes to precursors of residue B were developed. Careful optimisation of the glycosylation and oxidation reaction conditions gave the disaccharide building block AB equipped for the synthesis of chain extension at both ends. Selected mono- and disaccharide building blocks were validated by the synthesis of four disaccharides, bearing modification of the charge pattern or not, two trisaccharides and a tetrasaccharide
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Saliba, Regis C. "Design and synthesis of nanoparticles functionalised with Lewis oligosaccharides for selective targeting of DC-SIGN." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:21906fcb-b29f-415b-a1b7-bca375f06a2b.
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Dendritic cells (DC) are one of the major antigen presenting cells (APC) of the body. They, by capture of antigen and cross-presentation of these antigens, activate dormant T-cells and co-activate B-cells. As such they regulate the immune system toward either a more humoral type immune response or a more cellular type immune response. These properties have made them very studied over the past decade and many works have focus on the development of vaccine or therapeutic using DCs as a target. However, most of these actual studies have been done by injection of in vitro pre-activated DCs. The major drawback of this technique is the use of non-natural and non individual specific DCs (monocytes derived DCs and/or stem cells DCs). That is why therapeutic carrier targeting specifically DCs has to be developed. To achieve this goal, specific molecules present at the surface of DCs and involved in the activation of the immune system has to be targeted. Among them, DC-Specific ICAM-3 Grabbing Non-integrin CD209 (DC-SIGN) is very specifically expressed only on one subset of DCs called interstitial DCs. This lectin has been proven to be one of the first contacts of the DCs with T-cells and to induce one major interaction for cells proliferation of dormant T-cells. The goal of the project is to design a probe that can be used in vivo and post-mortem to target DCs via DC-SIGN. Therefore, we can use these particles as a proof of concept in vivo and in vitro, record the immune response obtained with them in vivo and in vitro and design probes that can be used to induce specific immune response for future therapy development. Lewis sugars have been shown to be quite specific to DC-SIGN. Their syntheses have been carried out in our lab with a cyanomethylthio linker at their anomeric position. This linker, once activated as a 2-imino-2-methoxyethyl moiety, has permitted the attachment of the oligosaccharides at the surface of dextran-coated iron oxide MRI nanoparticle. These particles have been chosen for their powerful properties and the advantage of the technique they are used for. Indeed, as particles their sizes mimic pathogens and DCs would interact with them, as they will with pathogen. Moreover, many copies of each oligosaccharide could be attached at their surface enhancing the interaction of the particles with the targeted lectin via a multivalent effect. As a technique, MRI has the advantage to be recorded over a long period of time (compare to 18F PET for example), with a relatively low signal/noise ratio (compare to fluorescence techniques) and without being harmful. FITC fluorescent Lewis X nanoparticles have been actually design and characterised (size by DLS, number of sugar by particles by ICP or fluorescamine fluorescence assay and binding affinity by ELISA with DC-SIGN-Fc). They have been first tested in vitro with models cells (Raji and monocytes derived DCs) for specific uptake assays, where they exhibit specific uptake and internalisation. Lewis-x nanoparticles have also been tested in vivo in a rat model and have been shown to be retained in Lymph nodes compared to control particles. Post mortem analysis appears to demonstrate that these particles were internalised by rat DCs and transported in the centre of the lymph node known as the T-cell region. Finally, cytokines and CD86 concentration measurement have shown that upon internalisation of the nanoparticles, DC maturated. In addition, an antigenic OVA peptide epitope was attached to the surface of the nanoparticles for future T-cell proliferation experiments. It will allow the determination of the immune response expected. In summary, we have developed an immunogenic MRI-active probe that can target specifically DC-SIGN via the interaction with Lewis antigens present at the surface of the probe and trigger DC maturation.
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Mason, Joanne Sheri. "Fluorescent tag methodology in enzyme-catalysed oligosaccharide synthesis." Thesis, University of Warwick, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342692.
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Lam, Son Ngoc. "Glycosyl iodides : a modern tool for oligosaccharide synthesis /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Obuchowska, Agnes K. "Acyl transfer in chemical synthesis of oligosaccharides." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ34056.pdf.
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Wacowich-Sgarbi, Shirley Ann. "Synthesis and conformational studies of constrained oligosaccharides." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0013/NQ60036.pdf.
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Hall, Jonathan David. "Studies towards the combinatorial synthesis of oligosaccharides." Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361723.
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Natunen, Jari. "Enzymatic synthesis of known and novel oligosaccharides." Helsinki : University of Helsinki, 1999. http://ethesis.helsinki.fi/julkaisut/mat/bioti/vk/natunen/.
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Claisse, Nathalie. "Préparation et modification d'oligosaccharides de cellulose par chimie douce bio-inspirée." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00849149.
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La valorisation de la biomasse saccharidique pour la production de dérivés biosourcés d'intérêt est un enjeu important. La cellulose est le polysaccharide le plus abondant sur Terre et représente une source de matière première considérable. Dans ce travail, de nouveaux procédés de dépolymérisation de la cellulose pour l'obtention contrôlée de cellodextrines sont décrits. Ils proposent une approche alternative plus douce aux procédés de production actuels en privilégiant l'utilisation d'enzymes, et de liquides ioniques comme solvants alternatifs. Ce travail rapporte l'élaboration de deux méthodes d'obtention contrôlée d'oligosaccharides à partir de cellulose et de cellulose acétate par combinaisons successives d'hydrolyses acide et enzymatique. Ces procédés ont permis l'obtention de cellodextrines de tailles ciblées avec de bons rendements, et constituent une voie prometteuse pour la valorisation de la cellulose en dérivés biosourcés. La deuxième partie de ce travail consiste en la modification chimio-enzymatique des oligosaccharides de cellulose produits pour leur valorisation en biomolécules d'intérêt, plus particulièrement dans le domaine de l'agrochimie. Les cellodextrines sont utilisées en tant que base saccharidique pour la synthèse d'analogues de lipo-chitooligosaccharides comme potentiels fertilisants verts. Deux méthodes de préparation ont été élaborées à l'aide des glycoside-hydrolases comme outils de synthèse. Les stratégies développées permettent un accès efficace à la synthèse d'analogues et peuvent être adaptées pour la production d'autres molécules.
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CHEN, WENDY YUNTIEN. "SYNTHESIS AND OLIGOSACCHARIDE PROCESSING OF IMMUNOGLOBULIN-M DURING B-CELL DIFFERENTIATION." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184207.
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In order to understand glycoprotein biosynthesis and processing, we have studied the glycosylation and intracellular assembly kinetics of murine IgM which are expressed functionally only at specific stages of B-cell differentiation by the corresponding tumor cell lines. We have shown that the majority of carbohydrate chains on intracellular IgM contain predominantly Man₈GlcNac₂ rate limiting step in the carbohydrate processing is the transport from the RER to the Golgi apparatus. We made comparisons of carbohydrate structures on secretory and membrane-bound u chains produced by different cell lines. Our results show that the carbohydrates on WEHI231 membrane-bound IgM are less processed, and the processing at individual glycosylation sites is different for IgMs produced by plasmacytoma (MOPC104E) and hybridoma (MPC11xW279.2) cell lines. In addition, we also show that the glycosylation and processing are dramatically altered by lowering the glucose concentration in the cell culture medium. These results are a beginning for our understanding of the influence of the polypeptide on the final glycosylation patterns of a glycoprotein, and the genetic and environmental control over the carbohydrate processing during intracellular transport. The kinetic studies on IgM synthesis and maturation in WEHI231 as well as WEHI279.1/12 cells have led to the conclusion that membrane bound IgM and soluble IgM are segregated and processed individually even in the same cell. These differences appear to lead to the changes in carbohydrate/processing for membrane-bound and soluble IgM.
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Apanga, Ludovic. "Mise au point de procédés de préparation d'oligosaccharides contenant du fucose à partir d'exopolysaccharides issus de souches mutées de bactéries du sol." Amiens, 2008. http://www.theses.fr/2008AMIE0116.
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Le L-fucose et les oligosaccharides contenant du L-fucose présentent des propriétés biologiques intéressantes notamment dans la prévention des métastases, dans la réaction d’inflammation, dans le traitement des arthrites rhumatoïdes, dans la vaccination (antigènes) et dans le domaine cosmétique contre la déshydration de la peau. Une production du L-fucose tout comme des oligosaccharides contenant du L-fucose en vue de leur utilisation dans des thérapies, a poussé des nombreux laboratoires à un screening des organismes synthétisant des polysaccharides contenant du L-fucose. Notre travail, s’est dans un premier temps sur la production et la caractérisation des polysaccharides des souches Sinorhizobium M5N1 cPRk290 notée N et Enterobacter notée Sc. Dans un second temps nous avons produit des oligosaccharides contenant du L-fucose dérivés des polysaccharides. Cette production d’oligosaccharides a nécessité l’utilisation de plusieurs méthodes (hydrolyse acide, hydrolyse thermique, production dans le milieu de culture et dégradation enzymatique). La méthode enzymatique a permis d’obtenir des oligosaccharides de manière reproductibleL-fucose and oligosaccharides containing of L-fucose present interesting biological properties notably in the prevention of the metastases, in the reaction of inflammation, in the treatment of rheumatoid arthritics, in the vaccination (antigens) and in the cosmetic domain against the dehydration of the skin. A production of L-fucose as of oligosaccharides containing of L-fucose with the aim of their use in therapies, pushed numerous laboratories to a screening of organisms synthetizing polysaccharides containing of L-fucose. Our work, concerned first of all the production of the polysaccharides by Sinorhizobium M5N1 cPRK290 noted N and Enterobacter noted Sc strains, later these polysaccharides were characterized. And secondly we produced oligosaccharides containing of L-fucose from polysaccharides. This production of oligosaccharides required the use of several methods (acid hydrolysis, thermal hydrolysis, in the medium of culture and enzymatic degradation). The enzymatic method allows to obtain oligosaccharides in a reproducible way
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Blomberg, Lennart. "Synthesis, coupling and use of oligosaccharides in affinity chromatography." Lund : Organic Chemistry 2, Lund Institute of Technology, Lund University, 1994. http://books.google.com/books?id=-A1rAAAAMAAJ.
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Nieder, Veronika. "Glycosidase-katalysierte Synthese und Charakterisierung von Nucleotid-Di- und Oligosacchariden." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=962322776.
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Gagné, Rodney A. "Design, synthesis and evaluation of high affinity oligosaccharide ligands." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0012/NQ59963.pdf.
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Chindarkar, Nandkishor S. "Synthesis, characterization, and application of novel multifunctional oligosaccharide tags." Scholarly Commons, 2008. https://scholarlycommons.pacific.edu/uop_etds/2378.
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Oligosaccharides play very crucial biological roles in the human body. They are structurally diverse and very challenging to analyze. In an attempt to contribute towards the analysis of oligosaccharides in the growing filed of 'Glycomics', we explored different ways to make novel efficient oligosaccharide tags to label N -linked oligosaccharides from glycoproteins. We synthesized and characterized various oligosaccharide tags which are useful to analyze the oligosaccharide by mass spectrometry, HPLC, and bioaffinity. In these tags we incorporated ar UV/fluorescent core, a biotin moiety and an amino/azido/alkyne terminus. We varied the structures of the tags for improved solubility in common organic solvents. These tags were used to label standard oligosaccharides, and the labeling efficiency was evaluated.
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Maosah, Charity Kwamboka. "Enhancing transglycosylation reaction by minimizing hydrolysis in oligosaccharide synthesis." Youngstown State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ysu161990153240475.
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Yamada, Takeshi. "A new iterative strategy of oligosaccharide synthesis using chalcogenoglycosides." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/144037.
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Kyoto University (京都大学)0048
新制・課程博士
博士(工学)
甲第12353号
工博第2682号
新制||工||1379(附属図書館)
24189
UT51-2006-J345
京都大学大学院工学研究科合成・生物化学専攻
(主査)教授 吉田 潤一, 教授 村上 正浩, 教授 杉野目 道紀
学位規則第4条第1項該当
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Ellervik, Ulf. "Synthetic analogs of sialyl Lewis x." Lund : Lund University, 1998. http://catalog.hathitrust.org/api/volumes/oclc/68945019.html.
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Chassagne, Pierre. "En route vers des glycoconjugués à potentiel vaccinal contre la dysenterie bacillaire : synthèse d'oligosaccharides représentatifs de l'antigène O de Shigella flexneri sérotype 6." Thesis, Paris 5, 2012. http://www.theses.fr/2012PA05P603.
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Nazabadioko, Serge. "Synthese d'oligosaccharides pour l'hemisynthese de saponines." Reims, 1996. http://www.theses.fr/1996REIMP202.
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Underwood, Melanie. "The synthesis of oligosaccharides related to heparan sulphate." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359986.
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Love, Kerry Routenberg 1977. "Automated synthesis of the Lewis blood group oligosaccharides." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/17827.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2004.Vita.
Includes bibliographical references.
Cell-surface carbohydrates are markers of specific cell types. These oligosaccharides are involved in recognition, adhesion, and signal transduction events. Advances in molecular glycobiology rely heavily on straightforward access to structurally defined oligosaccharides, but traditional syntheses of complex carbohydrates have been very laborious. Development of a novel linker and monitoring of each glycosylation reaction during automated solid-phase oligosaccharide synthesis allowed for the rapid synthesis of three Lewis-type cell surface oligosaccharides. The assembly of the nonasaccharide adenocarcinoma marker Le[superscript]y-Le[superscript]x monosaccharide building blocks was achieved in just 23 hours, while the syntheses of the tumor markers Lewis X, a pentasaccharide, and Lewis Y, a hexasaccharide, required only 12 and 14 hours respectively. The automation of carbohydrate synthesis greatly accelerates access to molecules for biological study and vaccine development.
by Kerry Routenberg Love.
Ph.D.
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Bouhall, Samantha K. "Preactivation Glycosylation of Oligosaccharide Molecular Probes for the Investigation of Mycobacterium tuberculosis Enzyme GlgE." University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1449787207.
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Rolland, David. "Nanofluidique de solutions polymériques appliquées à la synthèse in situ d'oligosaccharides." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00721738.
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Les biopuces connaissent un grand essor depuis quelques années avec des applicationspossibles pour l'ADN, les protéines et les oligosaccharides. Une puce à oligosaccharidesprésente des difficultés par rapport à une puce à ADN notamment par les contraintes entempérature et il existe moins de travaux dans ce domaine. Ce travail est donc consacré àl'étude d'une puce à oligosaccharide, par synthèse supportée et par masquage avec un film depolymère. Le procédé de fabrications est particulièrement détaillé.Nous étudions tout d'abord expérimentalement la formation d'un film de polymère obtenu parévaporation d'une goutte de solution polymérique sur une surface structurée chimiquement(zone de mouillabilité différente) en suivant son évolution transitoire. Nous montrons que cetype de surface hétérogène est particulièrement adapté pour la fabrication de biopuces.D'autre part, nous réalisons un modèle numérique de l'évaporation d'une goutte de solutionpolymérique sur une surface chauffée à partir de la méthode de la lubrification et d'un modèlede " hauteur de résine ". Les résultats expérimentaux et de simulation numérique sontcomparés et montrent un bon accord qualitatif sur la forme des films de polymères résultantde l'évaporation.Dans ce travail, la synthèse supportée de biopuces à oligosaccharide est menée à bien enutilisant des polymères et des surfaces judicieusement choisies. En particulier, la technique demasquage par film de polymère se révèle être très bien adaptée pour protéger les oligomères àla fois à hautes et à très basses températures.
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Cumpstey, Ian. "The stereospecific formation of 1,2-cis glycosides via allyl-mediated intramolecular aglycon delivery." Thesis, University of Oxford, 2002. http://ora.ox.ac.uk/objects/uuid:2c4e0fb3-5a43-473a-bfbb-43557f19ffe9.
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Douglas, N. L. "Tuning glycoside reactivity : a new tool for efficient oligosaccharide synthesis." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598613.
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This thesis is divided into four chapters. The first contains an introduction to oligosaccharides, including an overview of their role in nature and a summary of the difficulties and complexities in saccharide synthesis in the context of protection strategies. Selective glycosylation reactions, by control of donor reactivity, and the development of the armed/disarmed concept for saccharide coupling are discussed. The second chapter concerns research into the scope of selective glycosylations using competition reactions to evaluate the effects of protecting groups on the reactivity of glycosyl donors. A variety of protecting groups are studied with both rhamnose and mannose monosaccharides. The influence of the sugar type and of different anomeric leaving groups is also discussed. The third chapter deals with the application of data from chapter 2 to the design of oligosaccharide syntheses. A trisaccharide synthesis is planned whereby the protecting group strategy is developed to tune the reactivity of the monosaccharide building blocks. This enabled a "one-pot" procedure to be implemented, demonstrating the suitability of this methodology to the efficient synthesis of oligosaccharides.