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The MHC-glycopeptide-T cell interaction in collagen induced arthritis : a study using glycopeptides, isosteres and statistical molecular design in a mouse model for rheumatoid arthritisHolm, Lotta January 2006 (has links)
Rheumatoid arthritis (RA) is an autoimmune disease affecting approximately 1% of the population in the western world. It is characterised by a tissue specific attack of cartilage in peripheral joints. Collagen induced arthritis (CIA) is one of the most commonly used animal models for (RA), with similar symptoms and histopathology. CIA is induced by immunisation of mice with type II collagen (CII), and the immunodominant part was previously found to be located between residues 256-270. This thesis describes the interaction between the MHC molecule, glycopeptide antigens from CII and the T cells that is essential in development of CIA. The glycopeptide properties for binding to the mouse MHC molecule Aq have been studied, as well as interaction points in the glycopeptide that are critical for stimulation of a T-cell response. The thesis is based on five studies. In the first paper the minimal glycopeptide core, that is required for binding to the Aq molecule while still giving a full T cell response was determined. The second paper studied the roles of amino acid side-chains and a backbone amide bond as T-cell contact points. In the third paper the hydrogen bond donor-acceptor characteristics of the 4-OH galactose hydroxyl group of the glycopeptide was studied in detail. In the fourth paper we established a structure activity relationship (QSAR model) for (glyco)peptide binding to the Aq molecule. Finally, the stereochemical requirements for glycopeptide binding to the Aq molecule and for T-cell recognition was studied in the fifth paper. The study was performed using collagen glycopeptide analogues, which were synthesised on solid phase. Amide bond and hydroxyl group isosteres were introduced for study of hydrogen bond donor-acceptor characteristics. Statistical methods were used to design a representative peptide test set and in establishing a QSAR model. The results give a deeper understanding of the interactions involved in the ternary MHC-glycopeptide-T cell complex. This information contributes to research directed towards finding new treatments for RA.
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Spectroscopic data and multivariate analysis : tools to study genetic perturbations in poplar treesWiklund, Susanne January 2007 (has links)
In our society in the 21st century one of the greatest challenges is to provide raw materials to the industry in a sustainable way. This requires increased use of renewable raw materials such as wood. Wood is widely used in pulp, paper and textile industries and ongoing research efforts aim to extend the use of wood in e.g. liquid biofuels and green chemicals. At Umeå Plant Science Center (UPSC) poplar trees are used as model systems to study wood formation. The objective is to understand the function of the genes underlying the wood forming process. This knowledge could result in improved chemical and physical wood properties suitable for different industrial processes. This will in turn meet the demands for a sustainable development. This thesis presents tools and strategies to unravel information regarding genetic perturbations in poplar trees by the use of nuclear magnetic resonance (NMR) spectroscopy and multivariate analysis (MVA). Furthermore, gas chromatography/mass spectrometry (GC/MS) is briefly discussed in this context. Multivariate methods to find patterns and trends in NMR data have been used for more than 30 years. In the beginning MVA was applied in pattern recognition studies in order to characterize chemical structures with different ligands and in different solvents. Today, the multivariate methods have developed and the research have changed focus towards the study of biofluids from plant extracts, urine, blood plasma, saliva etc. NMR spectra of biofluids can contain thousands of resonances, originating from hundreds of different compounds. This type of complex data can be hard to summarize and interpret without appropriate tools and require sophisticated strategies for data evaluation. Related fields of research are rapidly growing and are here referred to as metabolomics. Five different research projects are presented which includes analysis of poplar samples where macromolecules such as pectin and also small molecules such as metabolites were analysed by high resolution magic angle spinning (HR/MAS) NMR spectroscopy, 1H-13C HSQC NMR and GC/MS. The discussion topics include modelling of metabolomic time dependencies in combination with genetic variation, validation of orthogonal projections to latent structures (OPLS) models, selection of putative biomarkers related to genetic modification from OPLS-discriminant analysis (DA) models, measuring one of the main components found in the primary cell-walls of poplar i.e. pectin, the use of Fourier transformed two-dimensional (2D) NMR data in OPLS modelling and model complexity in a PLS model.
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Dynamic Systems: Evaluation, Screening and Synthetic ApplicationSakulsombat, Morakot January 2011 (has links)
The research work reported in the thesis deals with the development of dynamic covalent systems and their applications in evaluation and screening of protein-ligands and enzyme inhibitors, as well as in synthetic methodologies. The thesis is divided into four parts as described below. In part one, synthetic methodologies to access 3-functionalized phthalides and 3-thioisoindolinones using the concept of cascade reactions are demonstrated. Efficient syntheses of the target products are designed and performed in one-pot process under mild reaction conditions. In part two, phosphine-catalyzed disulfide metathesis for the generation of dynamic carbohydrate system in aqueous solution is demonstrated. In the presence of biological target (Concanavalin A), the optimal dynamic ligand is successfully identified in situ by the 1H STD-NMR spectroscopy. In part three, lipase-catalyzed resolutions of dynamic reversible systems using reversible cyanohydrin and hemithioacetal reactions in one-pot processes are demonstrated. The dynamic systems are generated under thermodynamic control in organic solution and subsequently resolved by lipase-mediated resolution under kinetic control. The resolution processes resulted in the lipase-selected substrates with high structural and stereochemical specificities. In the last part, dynamic fragment-based strategy is presented using β-galactosidase as a model target enzyme. Based on our previous study, the best dynamic inhibitor of β-galactosidase was identified using 1H STD-NMR technique from dynamic hemithioacetal systems. The structure of the dynamic inhibitor is tailored by fragment linking and optimization processes. The designed inhibitor structures are then synthesized and tested for inhibition activities against β-galactosidase. / QC 20110526
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New Methodologies in Organic Chemistry: Applications to the Synthesis of α-Amino Acids and Natural ProductsHirner, Sebastian January 2009 (has links)
This thesis deals with the development and application of new synthetic methodology in organic chemistry. The first part describes the development of a new protocol for the synthesis of 3-pyrrolines by means of a microwave-assisted ring-expansion reaction of 2-vinylaziridines. In addition, this methodology is implemented as a key-step in a formal total synthesis of the antibiotic (-)-anisomycin. In the second part, a new methodology for the synthesis of arylglycines from Weinreb amides is described. In this procedure, a Grignard reagent is added to the iminium ion formed from the Weinreb amide upon treatment with a base. When a chiral amide is used, the nucleophilic addition proceeds with high diastereoselectivity. Finally, an easy and straightforward synthesis of α-amino amides via a base-mediated rearrangement of modified Weinreb amides into N,O-acetals is presented. Subsequent arylation, alkylation, alkenylation or alkynylation of this intermediate affords the corresponding α-amino amides in excellent yields. Furthermore, a more generalized protocol for the α-arylation of Weinreb amides lacking an α-amino moiety is also discussed. / QC 20100719
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Design, Synthesis and Properties of Organic Sensitizers for Dye Sensitized Solar CellsKarlsson, Karl Martin January 2011 (has links)
This thesis gives a detailed description of the design and synthesis of new organic sensitizers for Dye sensitized Solar Cells (DSCs). It is divided in 7 chapters, where the first gives an introduction to the field of DSCs and the synthesis of organic sensitizers. Chapters 2 to 6 deal with the work of the author, starting with the first publication and the other following in chronological order. The thesis is completed with some concluding remarks (chapter 7). The DSC is a fairly new solar cell concept, also known as the Grätzel cell, after its inventor Michael Grätzel. It uses a dye (sensitizer) to capture the incident light. The dye is chemically connected to a porous layer of a wide band-gap semiconductor. The separation of light absorption and charge separation is different from the conventional Si-based solar cells. Therefore, it does not require the very high purity materials necessary for the Si-solar cells. This opens up the possibility of easier manufacturing for future large scale production. Since the groundbreaking work reported in 1991, the interest within the field has grown rapidly. Large companies have taken up their own research and new companies have started with their focus on the DSC. So far the highest solar energy to electricity conversion efficiencies have reached ~12%. The sensitizers in this thesis are based on triphenylamine or phenoxazine as the electron donating part in the molecule. A conjugated linker allows the electrons to flow from the donor to the acceptor, which will enable the electrons to inject into the semiconductor once they are excited. Changing the structure by introducing substituents, extending the conjugation and exchanging parts of the molecule, will influence the performance of the solar cell. By analyzing the performance, one can evaluate the importance of each component in the structure and thereby gain more insight into the complex nature of the dye sensitized solar cell. / QC 20110505
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Inkjet deposition of electrolyte : Towards Fully Printed Light-emitting Electrochemical CellsLindh, Mattias January 2013 (has links)
Organic electronics is a hot and modern topic which holds great promise for present and future applications. One such application is the light-emitting electrochemical cell (LEC). It can be fully solution processed and driven at low voltage providing light emission from a large surface. Inkjet printers available today can print a variety of inks, both solutions and dispersions. The technique is scalable and a quick and easy way to accurately deposit small quantities of material in user definable patterns onto a substrate. This is desirable to make low cost and efficient optical devices like displays. In this thesis it has been shown that solid electrolytes, after being dissolved in a liquid solvent, can be inkjet printed into a set of well separated distinct drops with an average maximum thickness of 150 nm. The electrolytes are commonly used in LECs and comprised by poly(ethylene glycol) with molar masses ranging from 1 – 35 kg/mol, and potassium trifluoromethanesulfonate (KCF3 SO3 )—together dissolved incyclohexanone to form an ink. The smallest achieved edge to edge distance between the printed drops was 40 μm. Together with a drop diameter of 50 μm it yields a coverage of 24% at a resolution of 280 dpi. Profiles of dried deposited drops of electrolyte were examined with a profilometer, which showed adistinct coffee ring effect on each drop. In particular, the ridges of the coffee rings were broken into pillar like shapes, together forming a structure akin to a scandinavian ancient remnant called stone ship. Different drop diameters were measured in and between the indium tin oxide samples. The drops’ speeds and sizes atejection from the nozzles seemed unchanged, and wettability is most probably the physical phenomena tolook into in order to understand what generates the differences. Local changes in surface roughness and/or surface energy, possibly originating from the cleaning process of the samples, is most likely the cause. No indications towards large differences in surface tension between the printable inks were seen, however their viscoelastic properties were not measured. As part of the thesis work a LEC characterization set-up was built. It drives a LEC at constant currentand measures the driving voltage, -current, and luminance over time. The set-up is controlled by a Labview virtual instrument and the data exported to a text-file for later analysis. The precision of the luminance measurements is ±0.1 cd/m2 for readings < 50 cd/m2 , but the accuracy is uncertain. The conclusion of this thesis is that it is indeed possible to print solid electrolytes dissolved in cyclo-hexanone with an inkjet printer. However, in order to fully understand the spreading and drying of thedrops, studies of the inks’ viscoelastic properties, together with surface roughness and -energy density ofthe substrates, are needed. The largest molar mass of nicely printable poly(ethylene glycol), at an ink concentration of 10 mg/ml, was 35 kg/mol. This is comparable to the molar mass of an active light-emittingmaterial, “SuperYellow”, often used in LECs. Even though their respective molecular structures are very different, this indicates that inkjet printing of complete LEC-inks, containing both the active material and solid electrolyte, is feasible. Most probably it would require substantial tuning of the printing parameters. This thesis provides further hope for future fully inkjet printed LECs.
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Selective protein functionalisation via enzymatic phosphocholinationOchtrop, Philipp January 2017 (has links)
Proteins are the most abundant biomolecules within a cell and are involved in all biochemical cellular processes ultimately determining cellular function. Therefore, to develop a complete understanding of cellular processes, obtaining knowledge about protein function and interaction at a molecular level is critical. Consequently, the investigation of proteins in their native environment or in partially purified mixtures is a major endeavour in modern life sciences. Due to their high chemical similarity, the inherent problem of studying proteins in complex mixtures is to specifically differentiate one protein of interest from the bulk of other proteins. Site-specific protein functionalisation strategies have become an indispensable tool in biochemical- and cell biology studies. This thesis presents the development of a new enzymatic site-specific protein functionalisation strategy that is based on the reversible covalent phosphocholination of short amino acid sequences in intact proteins. A synthetic strategy has been established that allows access to functionalised CDP-choline derivatives carrying fluorescent reporter groups, affinity tags or bioorthogonal handles. These CDP-choline derivatives serve as co-substrates for the bacterial phosphocholinating enzyme AnkX from Legionella pneumophila, which transfers a phosphocholine moiety to the switch II region of its native target protein Rab1b during infection. We identified the octapeptide sequence TITSSYYR as the minimum recognition sequence required to direct the AnkX catalysed phosphocholination and demonstrated the functionalisation of proteins of interest carrying this recognition tag at the N- or C-terminus as well as in internal loop regions. Moreover, this covalent modification can be hydrolytically reversed by the action of the Legionella enzyme Lem3, which makes the labeling strategy the first example of a covalent and reversible approach that is fully orthogonal to current existing methodologies. Thus, the here presented protein functionalisation approach holds the potential to increase the scope of possible labeling strategies in complex biological systems. In addition to the labeling of tagged target proteins, a CDP-choline derivative equipped with a biotin affinity-tag was synthesised and used in pull-down experiments to investigate the substrate scope of AnkX and to elucidate the role of protein phosphocholination during Legionella pneumophila infection. / Proteiner utgör huvudbeståndsdelen av alla biomolekyler i en cell. Dessa är involverade i alla cellulära processer som bestämmer cellens egenskaper. För att förstå de cellulära processerna är det nödvändigt att förstå proteinernas funktion på molekylär nivå. Att studera proteiner i deras naturliga omgivning, det vill säga inuti en cell eller i ett cellextrakt, är en stor utmaning i dagens livsvetenskaper. Eftersom proteiner är kemiskt lika varandra så är det svårt att skilja ett från tusentals andra. Att specifikt märka proteiner för att skilja ut dem från bakgrunden har blivit ett viktigt arbetssätt i modern biokemi och cellbiologi. Avhandlingen beskriver utvecklandet av en ny metod för reversibel och kovalent enzymatisk märkning baserat på fosfokolinering/defosfokolinering av en kort aminosyrasekvens i intakta proteiner. En syntesmetod för att framställa onaturliga CDP-kolinderivat har etablerats vilket tillåter oss att framställa CDP-kolin som bär en funktionalitet, vilket kan vara ett färgämne eller en affinitetstagg. Dessa onaturliga CDP-kolinderivat accepteras som co-substrat av enzymet AnkX från Legionella pneumophila vilket transfererar den funktionaliserade delen av CDP-kolinderivatet till en kort aminosyrasekvens baserad på AnkX’s naturliga substrat vid infektion, det lilla GTPaset Rab1. Under avhandlingsarbetets gång identifierades den kortaste aminosyrasekvensen som känns igen av AnkX, endast de åtta aminosyrorna TITSSYYR är nödvändiga för igenkänning av AnkX. Dessa åtta aminosyror kan genetiskt infogas i början, slutet eller mitt i ett protein för igenkänning och funktionalisering via AnkX och våra syntetiska CDP-kolinderivat. Vid Legionellainfektion i eukaryota celler klyvs fosfokolineringen efter en viss tid, eftersom Legionella pneumophila producerar ett fosfodiesteras, Lem3, som tar bort de fosfokolineringar som AnkX har installerat när de inte längre behövs. Vi har använt Lem3 för att ta bort märkning i sekvensen TITSS(PC)YYR, vilket gör vår strategi helt reversibel. Vi har kunnat demonstrera att AnkX-Lem3 systemet accepterar ett brett spektrum av CDP-kolinderivat, vilket gör metoden till den första av sitt slag, eftersom den är fullt reversibel. Vi har vidare undersökt vilka proteiner AnkX reagerar med inuti celler, vi använde oss av ett CDP-kolinderivat funktionaliserat med biotin, vilket har tillåtit oss att fiska ut alla de proteiner som fosfokolineras av AnkX. Förutom de små GTPaserna i Rab-familjen så identifierade vi även IMPDH2, ett enzym som reglerar det hastighetsbestämmande steget i syntesen av guanosin-nukleotider. Detta är mycket intressant, eftersom det leder till frågan ifall Legionella pneumophila manipulerar sin värdcell genom att förändra mängden GTP i förhållande till ATP.
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Palladium(0)-Catalysed Carbonylative Multicomponent Reactions : Synthesis of Heterocycles and the Application of Quinolinyl Pyrimidines as Enzyme InhibitorsÅkerbladh, Linda January 2017 (has links)
Palladium-catalysed carbonylative multicomponent reactions have proven useful for the synthesis of structurally diverse compounds. Carbon monoxide serves as an atom-efficient, one-carbon building block, which allows for further structural elaboration of the carbonyl compound. By varying the components of the carbonylative multicomponent reaction, considerable product diversity can readily be attained. However, due to the reluctance to use toxic CO gas, considerable efforts have been directed at exploring non-gaseous approaches. The work described in this thesis has mainly focused on the development of palladium(0)-catalysed, carbonylative multicomponent synthetic methodology, using the non-gaseous CO source molybdenum hexacarbonyl, in the synthesis of heterocycles and other biologically relevant functional groups. The first part of this work describes the development of a non-gaseous carbonylative Sonogashira cross-coupling of bifunctional ortho-iodoanilines and terminal alkynes. Where 4-quinolones were synthesised via a carbonylation/cyclisation sequence. Using a similar synthetic strategy, three different N-cyanobenzamide intermediates were prepared by palladium-catalysed carbonylative couplings of various aryl halides and bromides and cyanamide. The formed intermediates provided a basis for further chemical transformations. First, ortho-iodoanilines were carbonylatively coupled with cyanamide and subsequently cyclised to yield heterocyclic 2-aminoquinazolinones. Next, building on those findings, the same synthetic strategy was applied to ortho-halophenols to provide a highly convenient domino carbonylation/cyclisation method for the preparation of benzoxazinones. The developed method was used to evaluate the efficiency of various non-gaseous CO sources. Third, the palladium-catalysed carbonylative synthesis of N-cyanobenzamides, was used to produce biologically relevant N-acylguanidines with considerable product diversity. Finally, one of the developed carbonylative methodologies was used in the preparation of potential NDH-2 inhibitors based on a quinolinyl pyrimidine scaffold. The prepared compounds were biologically evaluated in terms of inhibition of oxidoreductase NDH-2 and antibacterial activity on Gram-negative bacteria, S. aureus and Mtb. The biological evaluation revealed that some of the quinolinyl pyrimidines exerted inhibitory activity on the NDH-2 enzyme and possessed antibacterial properties. The work described in this thesis has been devoted to the development of non-gaseous one-pot, multicomponent carbonylation/cyclisation and carbonylation/amination reactions. The described methods offer highly attractive synthetic strategies that can be of great value to synthetic and medicinal chemists.
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Palladium(II)-Catalyzed Addition Reactions : Synthesis of Aryl Amidines and Aryl KetonesRydfjord, Jonas January 2017 (has links)
Palladium-catalyzed reactions have become one of the most important tools in modern organic chemistry due to its ability to catalyze the formation of new carbon-carbon bonds. The aim of the work presented in this thesis was to develop new palladium(II)-catalyzed addition reactions. In this work, cyanamides were investigated as a new substrate to give aryl amidines as products. The first protocol developed employed aryltrifluoroborates as the aryl partner, and the insertion of the aryl group into un-, mono-, and di-substituted cyanamides was successful for a wide variety of aryltrifluoroborates. An alternative method of generating the necessary intermediate for insertion into the cyanamide is the decarboxylative formation of aryl-palladium from aryl carboxylic acids. A protocol was developed for this reaction, but was unfortunately limited to a small number of ortho-substituted electron-rich aryl carboxylic acids. The mechanism was investigated by the means of DFT calculations and ESI-MS studies, and the rate-determining step was suggested to be the 1,2-carbopalladation based upon those results. A translation of the batch protocol to continuous-flow conditions was also demonstrated. The ideal method of generating the aryl-palladium species is by C-H bond activation, and this approach was demonstrated with indoles, giving a variety of 3-amidinoindoles as products. The mechanism was investigated by DFT calculations and a plausible catalytic cycle was proposed. A continuous-flow application of a desulfitative palladium(II)-catalyzed addition to nitriles to give ketones was developed. In addition, different reactor materials were evaluated in the microwave heated reactor cavity. Thus the reaction was shown to proceed with microwave heating in a borosilicate glass and an aluminum oxide reactor, and also in conditions mimicking conventional heating in a silicon carbide reactor. Finally, a protocol was developed for the convenient synthesis of sodium aryl sulfinates from Grignard and lithium reagents using a solid sulfur dioxide source as a safe alternative to the gas. The products of this protocol can be used as aryl-palladium precursors by a desulfitative process.
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Metals in Dynamic Chemistry: Selection & CatalysisTimmer, Brian J.J. January 2017 (has links)
In the adaptation to the oxidative environment on earth, metals played a crucial role for the evolution of life. The presence of metals also allowed access to advanced functions due to their unique coordination sphere and reactivity. This thesis focused on exploiting these unique properties for further development of the field of dynamic chemistry – a field in which adaptation plays a central role as well. The first part of the thesis aimed to create a better understanding of multivalent effects in carbohydrate-lectin interactions. By reversible ligand coordination to zinc ions one of the nanoplatforms, the Borromean rings, could be selectively obtained. After carbohydrate functionalization the binding events were monitored by quartz crystal microbalance technology and compared to glycosylated fullerenes and dodecaamide cages. Overall, this investigation indicated that statistical and polyelectrolyte effects play a considerable role in the observed multivalent effects. The second part of the thesis aimed to design and synthesize a new catalyst for application in aqueous olefin metathesis. This afforded a ruthenium based catalyst that was applied in the self- and cross-metathesis of highly functionalized substrates, such as carbohydrates. In addition, it was shown that addition of a small amount of acetic acid prevented undesired double bond isomerization. The last part of the thesis aimed to explore new methods to discover transition metal catalysts. Dynamic exchange of directing groups generated a pool of potential substrates for C-H activation. Combining this pool of substrates with a pool of potential catalysts resulted in amplification of a reactive substrate/metal combination. By iterative deconvolution in combination with mass spectrometry, this “intermediate” could be identified from the mixture, proving applicability of this alternative approach to catalyst discovery. / <p>QC 20170809</p>
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