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  • 1.
    Bengtsson, Linda
    KTH, Skolan för kemivetenskap (CHE).
    Odorant binding protein and olfactory receptors: plausible role as detectors in an odorant biosensor2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The development of an inexpensive, portable, stable, sensitive and selective biosensor for detection of odorants is a daunting task. Here, we hypothesized the development of a detector layer composed of the protein groups; the olfactory receptors (ORs) and the odorant binding proteins (OBPs), known to bind odorants in animal sensing. We report the design of 13 OR gene-vector constructs, and their subsequent transformation into

    Escherichia (E.) coli (BL21 (DE3)-STAR-pLysS) strain. Moreover, we report the expression of several ORs into an in vitro wheat germ extract using three separate detergent mixes for protein solubilization.

     

    In addition, we describe the design of an odorant binding protein from the Aenopheles gambiae mosquito PEST strain (OBP-PEST) gene-vector construct under an IPTG (Isopropyl β-D-1-thiogalactopyranoside) inducible promoter. OBP-PEST was heterologously expressed in E.coli with an 8 amino acid long sequence (WSPQFEK) attached C-terminally, via a thrombin cleavage site and a flexible linker (GSSG). The WSPQFEK sequence, commonly referred to as a Strep-tag, enabled subsequent affinity chromatography purification of the protein, via binding to an engineered Streptavidin equivalent. Surprisingly, the OBP-PEST was found to contain a signal sequence leading to its truncation and secretion when expressed in E.coli.

     

    Biophysical analyses were established using Circular Dichroism (CD) for the analysis of two lipocalins: Beta-lactoglobulin (BLG) and OBP-PEST. We studied the solubility, refoldability and the conformational transitions of BLG, as a result of change in solvent, pH and temperature. The secondary structure of OBP-PEST and its thermal stability was investigated.

     

    In conclusion, this thesis work has enabled biophysical analyses of OBP-PEST and future analogs of interest to the development of a stable protein detector layer. Although further experiments are needed to fully characterize the biophysical properties, and to find odorant substrates of OBP-PEST, it was found to be a suitable alternative to ORs in a biosensor detector layer application. More importantly, an inherent OBP-PEST signal sequence was found to mediate protein secretion when expressed heterologously in E.coli. To the best of our knowledge this is the first lipocalin discovered to be secreted upon heterologous expression in E.coli.

     

    We hypothesize that this signal peptide could be used as a means for targeted secretion and, hence, efficient protein purification.

  • 2.
    Blomkvist, Björn
    KTH, Skolan för kemivetenskap (CHE).
    The application of reversible covalent bonds in catalysis2014Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I detta projekt har ligandutbyte på trimetylborat, samt dess möjlighet att inducera intramolekularitet studerats. Experiment har utförts som inriktats på en fördjupad förståelse för boraffiniteten hos alkoholer och aminer, samt jämvikterna i dessa system. Vidare har reaktioner screenats i sökandet efter en reaktion som kan katalyseras av inducerad intramolelcularitet av trimetylborat.

  • 3.
    Fauquet, Germain
    KTH, Skolan för kemivetenskap (CHE).
    Reconnaissance biomoléculaire, Comparaison de l'impact du soufre et de l'oxygène dans la liaison glycosidique2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Interactions between carbohydrates and proteins play a key role in many biological processes. Cell-cell interactions, cell communication and cell proliferation are examples of processes based on highly specific interactions between proteins and complex oligosaccharides. The synthesis of carbohydrate mimics is essential for the study and understanding of such recognition processes, and has therefore become increasingly popular over the latest decades. In synthesis, thiol derivatives have several advantages. Thus, the combined nucleophilicity and chemical stability of sulfhydryl groups render thiol carbohydrate analogs as excellent building blocks for glycosylation processes. The objectives of the present project were to investigate the differences between naturally occurring oligosaccharides and their sulfur-analogs in biomolecular interactions with specific proteins. Convenient methodologies to the synthesis of a range of D-mannopyranose thioanalogs were developed. These strategies allows for the access to 1,2- and 1,6-linked dimannosides by glycosylation. A carbohydrate-protein interaction methodology to test the developed compounds against a mannose-specific lectin (Concanavalin A) using quartz crystal microbalance (QCM) methodology was furthermore developed.

  • 4.
    Fouilland, Laura
    KTH, Skolan för kemivetenskap (CHE).
    Synthesis of novel 1.10-phenanthrolins and cyclic analogs, a potential anticancer and antimalarial agents2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Tidigare studier har indikerat att molekyler med 1,10-phenanthrolineskelett har en skyddande effekt mot malaria och cancer. Syftet med detta projekt är att syntetisera nya 1,10-phenanthrolinar och cykliska analoger. Framställningsmetoden som användes i denna studie har inte undersökts tidigare. 

     

    Föreningen skapades genom en originalmetod utnyttjande en redoxreaktion med hjälp av en TDAE-reagens. TDAE är en elektronrik organisk molekyl och fungerar som en effektiv reduktionsagent. Med hjälp av en enelektronöverföring (SET) kan en anjon framställas under milda förhållanden utifrån halogena derivat. Anjonen tillförs 1,10-phenanthroline-5,6-dione. De olika substraten är heteroaromatiska nitro-benzyliska och quinoniska derivat, samt bromodifluorometylheteroarylerade. Cykliska produkter erhölls genom en tvåstegsreaktion (reduktion, dehydratisering) genomförd i ett enda reaktionskärl.

     

    Med detta projekt har dessa reaktioner för första gången testats på den här typen av molekyler. Det krävs mer optimering eftersom utbytena var låga till medelhöga. Utav sex möjliga substrat fungerade additionsreaktionen med TDAE med fyra stycken. I detta försök testades dock endast en cyklisk reaktion på additionsprodukten. Med ytterligare förbättringar av reaktionsvillkor och upparbetningar förväntas man kunna producera önskad produkt i gott utbyte.

  • 5.
    Goy, Michel
    et al.
    KTH, Skolan för kemivetenskap (CHE).
    Jakobsson, Catharina
    KTH, Skolan för kemivetenskap (CHE).
    Kartläggning av allergiframkallande hårfärgningsämnen i toningar i Stockholm2017Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    En vanlig källa till kontakallergiskt eksem är sensibiliserande (allergiframkallande) kemikalier som finns i hårfärger. Permanenta hårfärger innehåller kraftiga allergener, men det saknas kartläggande forskning på toningar. För att ta reda på vilka allergener som ingår i toningar behöver dagens utbud kartläggas. Detta projekt har skett i Stockholm och innehållet i sex olika märken har kartlagts. Toningar och permanenta hårfärger skiljer sig åt genom att permanenta hårfärger polymeriseras i håret genom oxidation med väteperoxid. Toningar innehåller kromofora ämnen som fäster i håret, antingen genom diffusion eller adsorption. Totalt kunde tio kromofora ämnen med kända sensibiliserande egenskaper hittas i toningarna varav en möjlig cancerogen. I varje produkt fanns i snitt 0,4–2,4, och som mest tre, kända sensibiliserande kromofora ämnen. Hårfärger utan sensibiliserande färgämnen kunde hittas i alla kulörer utom svart och brun. Även sensibiliserande parfymämnen och konserveringsmedel kunde påvisas. Eftersom det finns hårfärger i de flesta kulörer utan sensibiliserande färgämnen bör dessa ämnen fasas ut.

  • 6.
    Heid, Berenice
    KTH, Skolan för kemivetenskap (CHE).
    Enantioselective Preparation of ω-Functionalized O-Acylated Cyanohydrins2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    A minor enantiomer recycling one-pot process usingω-functionalized prochiral aldehydes as starting materials and two reinforcing catalysts has been reported. The desired aldehyde for these process studies was 5-bromo-1-pentanal.

    In a two-phase solvent system, enzyme-catalyzed hydrolysis of the minor enantiomer regenerates continuously the prochiral starting material and Lewis acid catalysed addition of acetyl cyanide provides the O-acetylated cyanohydrins. The minor enantiomer recycling process has been studied and improved for 5-bromo-1-pentanal to receive high enantiomeric excess and yield of the expected O-acetylated cyanohydrin.

  • 7.
    Kinschel, Dominik
    KTH, Skolan för kemivetenskap (CHE).
    Stable Redox Systems for Dye-Sensitized Solar Cells2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Dye sensitized solar cells are a new type of solar cells which open a new market thanks to their unique properties, which are semi transparency and the fact that they can be produced in various colors.

    After improving two existing syntheses for industrial applications, this thesis takes the approach to develop new redox mediators for devices with an aim on improving stability. Five redox mediators with cobalt, copper and iron as metal center were synthesized and characterized by NMR spectroscopy, cyclic voltammetry and UV/VIS spectrophotometry. Three of them were selected for evaluation in test cells. Most promising results were obtained with a copper complex, using the tandem redox approach a new record efficiency of 7.7% for copper based electrolytes in dye-sensitized solar cells was obtained.

  • 8.
    MOTOKI, YOSHIDA
    KTH, Skolan för kemivetenskap (CHE).
    Synthesis of Ruthenium-based Water Oxidation Catalysts and Mechanistic Study2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Two series of new mononuclear ruthenium complexes with hydrophobic or hydrophilic ligands [Ru(bda)L2] and [Ru(pdc)L3] (H2bda = 2,2'-bipyridine-6,6'-dicarboxylic acid; H2pdc = 2,6-pyridinedicarboxylic acid; L = pyridyl ligands) were synthesized and their electrochemical properties and catalytic activity toward water oxidation were examined. It was revealed that the hydrophobic ligands introduced to [Ru(bda)L2 ] improved the catalytic performance, ahnost twofold TON and TOF values were achieved compared to the [Ru(bda)] catalyst with hydrophilic ligands. The cyclic voltammogram of [Ru(bda)L2] exhibited marginal difference between the catalysts with hydrophobic ligands and hydrophilic ones, implying that the hydrophobic ligands promoted the catalytic activity by :lacilitating formation of a reaction intermediate dimer.

  • 9.
    Saur, Ann-Kathrin
    KTH, Skolan för kemivetenskap (CHE).
    Synthesis of α1,2- and α1,6, linked Dimannosides for Analysis of Protein Carbohydrate Interactions2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The aim of the project was to synthesize α1,2-linked and α1,6-linked dimannosides linked through either an oxygen-atom or a sulphur-atom, and subsequently test the binding properties of the dimannosides to lectins with known specificity towards mannose-containing glycans. Thedimannosides were prepared by a glycosylation reaction using selectively protected monosaccharides containing a thiol or alcohol nucleophilic glycosyl acceptor and a series of different glycosyl donors. The synthetic routes to the different building blocks were designed to efficiently make use of common intermediate compounds to streamline the synthesis. The glycosyl acceptors used forthe synthesis of α1,2-linked as well as α1,6-linked dimannosides were synthesized in few steps and diversified only in the last steps of the synthesis. The glycosyl donors used in the study were synthesized from commercially available starting material in a straightforward and convenientsynthesis in 7 to 8 steps.

  • 10.
    SEIGEL, KAROLINA
    KTH, Skolan för kemivetenskap (CHE).
    Hydrogen Bonding Catalysis of Imine Exchange with Thiourea and Squaramide Donors2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

     

    Syftet med detta projekt har varit att utforska möjligheten för aromatiska tioureor och skvaratamider att katalysera en reversibel iminutbytesreaktion genom vätebindningskatalys. Det primära målet var att finna en organokatalysator som skulle kunna ersätta eller vara ett komplement till befintliga katalysatorer för att möjliggöra nya tillämpningar. Flera parametrar såsom katalysatorns sammansättning och koncentration samt beroendet av lösningsmedel och vattenmängd har undersökts. Resultaten tyder på att ett lågt pKa för de vätebindningsdonerande väteatomerna och ett polärt och ickekoordinerande lösningsmedel är väldigt viktigt för att nå jämvikt på kort tid. Katalysatorerna har dessutom visat sig ha hög aktivitet även vid låga koncentrationer och förmågan att katalysera mer än ett steg i utbytesreaktionen. Tiden för att uppnå jämvikt bestämdes genom att regelbundet mäta integralerna för iminernas signaler i ett 1H NMR-spektrum, medan reaktionen pågick.

  • 11.
    Sjölin, Olof
    KTH, Skolan för kemivetenskap (CHE).
    Synthesis of Substituted Pyrrolidines2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The task of medicinal chemists in a drug discoveryproject is to synthesize/design analogues to the screening hits, simultaneouslyincreasing target potency and optimizing the pharmacological properties.  This requires a wide selection of moleculesto be synthesized, where both synthetic feasibility and price of startingmaterials are of great importance. In this work, a synthetic pathway from cheapand readily available starting materials to highly modifiable 2,4-disubstitutedpyrrolidines is demonstrated. Previously reported procedures to similarpyrrolidines use expensive catalysts, requires harsh conditions and requiresnon-commercially available starting materials. The suggested pathway herein has demonstrated great possibility forvariation in the 4-position, including fluoro, difluoro, nitrile and alcoholfunctional groups. There are several areas in which the synthesis can beimproved and expanded upon. Improvements can be made by optimizing thedescribed reaction conditions and further expansion of possible modificationsin both 2- and 4-position could be explored.

  • 12.
    Song, Yan
    KTH, Skolan för kemivetenskap (CHE).
    Regio- and Stereoselectivity in Glycosyl Disulfide Desulfurization. Generation of S-linked Disaccharides2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This report describes the synthesis of thiomonosaccharides and the subsequent oxidation to carbohydrate disulfides followed by evaluation of a desulfurization reaction with the aim of developing a facile method for production of S-linked oligosaccharides. The carbohydrate disulfides were synthesized in few steps from commercially available starting materials. Small and simple disulfides were used to evaluate the desulfurization process yielding important information about choice of solvent, catalyst and temperature required for the desulfurization to occur. The optimized conditions were then applied to the carbohydrate disulfides. Results showed that the reactivity of the carbohydrate disulfides depends a lot on the position of the disulfide. One of the carbohydrate disulfides was efficiently desulfurized giving the thioether linked disaccharide, as determined by mass spectrometry. However, more work is needed to develop a general procedure for the desulfurization working on many different carbohydrate disulfides.

  • 13.
    Starkholm, Allan
    KTH, Skolan för kemivetenskap (CHE).
    Synthesis of Water-Soluble Catalysts for Olefin Metathesis2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The need of efficient and sustainable chemical processes in the field of organic chemistry is essential in order to meet the environmental demands that societies and industries require from us. One key chemical reaction that is widely used in industrial plants is olefin metathesis, a reaction that involves exchange and formation of C-C double bonds. It is a crucial reaction in polymerization reactions and as a means of connecting building blocks together. Consequently it is necessary to enable these reactions to work in aqueous media for increased sustainability and for applications in biochemistry. Carbenes are a class of compounds that constitute a crucial role as ligands in olefin metathesis catalysts. This project will aim to explore the water applicability of a certain category of carbenes, cyclic (alkyl)-(amino)carbenes (CAAC), which recently have caught attention due to their remarkable catalytic activity in organometallic catalysis. The CAAC based catalysis display high stability towards air and moisture, and thus making them attractive alternatives for industrial applications. Throughout the project, synthetic routes towards water soluble CAAC:s have been designed and investigated. Moreover, an approach of evaluating a CAAC-ruthenium catalyst in micellar solutions have been investigated and illustrated promising results regarding activity and stability.

  • 14.
    Widing, Joakim
    KTH, Skolan för kemivetenskap (CHE).
    Preparation of Affinity Based Probes to Elucidate the Mode of Action of y-Secretase Modulators2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    γ-Secretase is an enzyme that takes part of the breakdown of amyloid precursor protein (APP) into amyloid-β (Aβ) peptides. Aβ-peptides from this process can be linked to Alzheimer’s disease. γ-Secretase modulators (GSMs) have been reported in the literature to reduce the potentially dangerous variant of Aβ-peptides. However, the mechanism of the binding site for these modulators is poorly understood. In this report substances of affinity based probes (AfBPs) have been prepared that can be used as a method to extract the binding site. The AfBPs were constituted of a cross-linking group, a biotinyl group and a γ-secretase modulator. Different variants of the biotin probe were prepared to investigate if the activity of the original modulator could be retained. The report will show that this could be done.

    In the future, the synthesised affinity based probes could be used to understand the mode of action of γ-secretase modulators. For instance the modulator could be incubated with the enzyme and the crosslinking group, when activated, covalently bind to a residue near the binding site. The complex could then be captured on avidin and the binding site be determined.

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