De nos jours, le scénario d’une pandémie à l’échelle mondiale est de plus en plus surveillé par l’Organisation mondiale de la santé en plus d’être exploité par le cinéma et les médias à sensations fortes. La réalité est que plusieurs épidémies ont ravagé la population sur terre à travers les époques telle que ce fut le cas lors de l’éclosion de la peste noire au XIV siècle en Europe et en Asie ou encore le VIH en Afrique encore aujourd’hui. La grande majorité des populations étant concentrée dans des mégalopoles et le transport international étant toujours plus développé et accessible rend une simple épidémie susceptible de se transformer rapidement en pandémie. Plus récemment, l’éclosion de la grippe aviaire H5N1 a décimé d’importantes populations d’oiseau en Asie et certains cas de contamination humaine fatale ont même été répertoriés. Comme les virus mutent rapidement, il serait donc pertinent de connaître leurs mécanismes de prolifération et tenter de les maîtriser afin de les neutraliser avant l’éclosion d’une souche se propageant d’humain à humain. Or, il a été découvert qu’une famille d’endoprotéases à sérines, les proprotéines convertases, sont impliquées dans diverses pathologies dont l’influenza-A H5N1. La furine, première proprotéine convertase à avoir été découverte, semble à l’origine de l’activation de ces virus. Nous avons donc choisi d’entreprendre la conception de divers inhibiteurs de furine dans le but de développer un agent antiviral contre cette pathologie. En ayant une approche impliquant la biologie structurelle et en effectuant une conception rationnelle d’inhibiteurs, nous avons développé des inhibiteurs de furine ayant à la fois une bonne affinité pour l’enzyme ainsi qu’une bonne stabilité en milieu biologique, tout en tentant de comprendre les principes fondamentaux de la liaison avec ces enzymes. Nos résultats ont démontré que diverses techniques peuvent être exploitées afin de concevoir des composés pouvant cibler la furine avec une bonne affinité. Le rationnel derrière la conception de ces composés a été démontrée à l’aide d’outils modernes de visualisation tridimensionnels de biomolécules en mettant en évidence les fonctionnalités importantes des complexes enzymes-substrat et enzyme-inhibiteurs afin de bien vulgariser la biologie structurelle inhérente au projet.

Protein adsorption on solid surfaces is a common yet complicated phenomenon that is not fully understood. Self-assembled monolayers have been utilized in many studies, as well-defined model systems for studying protein-surface interactions in the atomic level. Various strategies, including the use of single component SAMs[1, 2], combinations of long and short alkanethiolates with methyl- and hydroxyl- terminal groups[3, 4], and using mixtures of alkanethiolates with similar chain length and varying terminal functional group [5] have been used to effectively control the surface wettability and determine the effect of surface composition and wettability on protein adsorption. In this dissertation we report key new findings on the effect of surface density of functional groups on protein adsorption phenomenon. In The first phase of this research, we developed a novel approach for preparation of low-density self-assembled monolayers(LD-SAMs) on gold surfaces, based on radical-initiated thiol-yne click chemistry. This approach provides exceptional adsorbate stability and conformational freedom of interfacial functional groups, and is readily adapted for low-density monolayers of varied functionality. The resulting monolayers have two distinct phases: a highly crystalline head phase adjacent to the gold substrate, and a reduced density tail phase, which is in contact with the environment. First, we investigated the feasibility of the proposed chemistry in solution-phase. In this approach, we synthesized “Y” shaped carboxylate-terminated thiol adsorbates via radical-initiated thiol-yne reaction. The LD-SAMs were then prepared through immersion of gold substrates into the solution of synthesized adsorbate molecules in hexane. The chemical structuring and electrochemical properties of resultant LD-SAMs were analyzed and compared with those of analogous traditional well-packed monolayers, using techniques such as Fourier transform infrared spectroscopy, ellipsometry, electrochemical impedance spectroscopy, reductive desorption, and contact angle goniometry. Characterization results indicated that resulting LD-SAMs have a lower average crystallinity, and higher electrochemical stability compared to well-packed monolayers. In addition, using a three-electrode system, we were able to show a reversible change in LD-SAM surface wettability, in response to an applied voltage. This remodeling capacity confirms the low density of the surface region of LD-SAM coatings. The second area of work was focused on using the developed chemistry in solid-phase. The solid-phase approach minimized the required synthesis steps in solution-phase method, and used the photo-initiated thiol-yne click-reaction for grafting of acid-terminated alkynes to thiol-terminated monolayers on a gold substrate to create similar LD-SAMs as what were prepared through solution-phase process. We characterized the resulting monolayers and compared them to analogous well-packed SAMs and the also low-density monolayers prepared through the solution phase approach. The results confirmed the proposed two-phase structure, with a well-packed phase head phase and a loosely-packed tail phase. In addition, the electrochemical studies, indicated that the resultant monolayers were less stable than the monolayers prepared via solution-phase, but they are yet significantly more stable than typical well-packed monolayers. The less stability of these monolayers were attributed to the partial desorption of adsorbates from the gold substrate due to UV irradiation during the grafting process. Building on the established chemistry, we studied the effect of lateral packing density of functional groups in a monolayer on the adsorption of Bovine serum albumin protein. we used surface plasmon resonance spectroscopy (SPR) and spectroscopic ellipsometry, to evaluate BSA adsorption on carboxylate‑, hydroxyl-, or alkyl- terminated LD-SAMs. It was found that for the LD-SAMs, the magnitude of protein adsorption is consistently higher than that of a pure component, well-packed SAM for all functionalities studied. In addition, it was seen that the magnitude of BSA adsorption the LD-SAMs, was consistently higher than that of a pure component, well-packed SAM for all functionalities studied. The difference of protein adsorption on LD-SAMs and SAMs can not be associated to difference in lateral packing density, unless we eliminate the impact of other contributing factors in protein adsorption such as surface energy. In order to better understand the impact of packing density on protein-surface interactions, we prepared the mixed SAMs of (carboxylate/alkyl) and (hydroxyl/alkyl) with matching surface energy as the carboxylate and hydroxyl terminated LD-SAMs. It was found that the energy-matched mixed SAMs of carboxylate and hydroxyl functionality adsorbed more protein than the LD-SAMs. However, an opposite trend was seen for the alkyl surfaces, where surface energies are comparable for LD-SAMs and pure component SAMs, indicating that BSA proteins have higher affinity for methyl- terminated LD-SAMs than well-packed SAMs.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The creation of nanometer-scale (nanoscale) materials has fascinated and inspired the scientific community for more than a quarter of a century because of the wide range of applications of these materials, e.g. applications in drug delivery, medicine, tissue engineering, memory storage, display and audio devices, semiconductors, etc. π-Conjugated dendrimers have a proposed flat packing arrangement. An alternating phenyl isoxazole dendrimer system was developed to investigate this phenomenon. The synthesis of this dendritic system was attempted by divergent and convergent approaches. Preparation of the second generation failed because some functional groups inhibited the monomers to react to the first generation. Other examples of nano materials that have attracted a vast amount of interest are the so-called discotic amphiphiles. Discotic amphiphilic molecules have the potential to self-assemble into helical architectures. Discotic systems bearing chiral polar side chains (one and three respectively) were developed. Their self-assembly was investigated in variable concentration and variable solvent composition experiments. These systems did show signs of aggregation in UV-vis and CD spectroscopy experiments. Thread-like helical structures were observed with transmission electron microscopy. / AFRIKAANSE OPSOMMING: Nanometer-skaal materiale inspireer en fassineer wetenskaplikes al vir meer as 25 jaar as gevolg van hulle wye verskeidenheid toepassings bv.: die vervoer van geneesmiddels, weefsel ontwerp, geheue stoorspasie, digitale skerms, klank toerusting, geleiers, ens. π-Gekonjugeerde dendrimere het 'n plat drie dimmensionele rangskikking. 'n Afwisselende feniel isoxazole dendrimer stelsel was ontwikkel om hierdie verskynsel te ondersoek. Die sintese van hierdie dendritiese stelsel is aangepak deur divergerende en konvergerende benaderings. Sintese van die tweede generasie het misluk omdat sommige funksionele groepe die monomere geïnhibeer het om te reageer met die eerste generasie. Ander interessante voorbeelde van nano materiale, is die sogenaamde skyfvormige amphiphiles. Skyfvormige amphiphiles het die potensiaal om spontaan te versamel in heliese strukture. Skyfvormige molekules met chirale polêre sykettings (een en drie onderskeidelik) is ontwikkel. Hulle potensiaal om spontaan te versamel is ondersoek met wisselende konsentrasie en wisselende oplosmiddel samestelling eksperimente. Hierdie stelsels het tekens van versameling gewys in UV-vis en CD-spektroskopiese eksperimente. Staaf-vormige heliese strukture is waargeneem met transmissie-elektronmikroskopie.

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Cancer is the leading cause of death on the planet, killing an estimated 8.2 million people in the year of 2012.The disease is associated with two families of genes, namely oncogenes and tumour suppressor genes. The hallmarks of cancer pathogenesis include gene amplification, point mutations or chromosomal rearrangements within these genes. Kinases are responsible for the reversible phosphorylation of proteins, which plays a significant and extensive role in cellular signal transduction. Aberrant kinase activity provokes overexpression, mutations and chromosomal translocation and results in the onset of onco- and tumorogenesis, ultimately leading to cancer. Inactivation of this class of enzyme is thus critical as it would result in the suppression of these unwanted activities. For this, researchers have developed kinase inhibitors, specifically targeting these proteins and thus inhibiting signal transduction pathways and tumour growth. This has resulted in great successes, particularly in the case of the commercial inhibitor, imatinib. However, resistance to approved therapeutic agents through mutations has resulted in the search for more potent and selective inhibitors to overcome these obstacles. This project involved the synthesis of bioactive heterocycles linked to 1,2,3-triazoles using either a C-C or C-N bond forming strategy. The synthetic methodology followed included the use of Sonogashira coupling reactions between3-bromoquinoline, 7-chloro-4-iodoquinoline, 4-bromoisoquinolineand5-bromoisoquinolineand trimethylsilylacetylene (TMSA), followed by deprotection of the TMS group to yield heterocycles bearing terminal alkynes. The synthesis of both benzyl azide and 2-(azidomethyl)pyridine as azide fragments, allowed for subsequent coupling of the synthesized azide and alkyne fragments through copper-mediated click chemistry, affording a library of 1,4-substituted 1,2,3-triazole based reversible kinase inhibitors. Synthesis of a second library of o-, m- and p-substituted nitro benzyl azides, allowed for both copper- and ruthenium-mediated click reactions, between the alkynes and nitro benzyl azides synthesized, to yield 1,4- and 1,5-substituted 1,2,3-triazoles, respectively. Finally, reduction of the incorporated o-, m- and p- substituted nitro group, and acylation of the resultant amine with acryloyl chloride, resulted in the incorporation of the important Michael acceptor moiety required for irreversible inhibition. This afforded a library of both reversible and potential irreversible triazole-based kinase inhibitors through efficient copper- and ruthenium-mediated click chemistry. Biological screening and activity assays against the wildtype, and two mutated forms of the EGFR kinase, were undertaken with these synthesized compounds.A number of synthesized inhibitors showed good selectivity for the mutated forms of the EGFR kinase only.The most potent inhibitor N-{2-{[4-(isoquinolin-4-yl)-1H-1,2,3-triazol-1-yl]methyl}phenyl}acrylamide,displayed efficacy in the low μM range - comparable to that of the FDA approved drug, gefitinib. The synthetic methodology derived in this project could be applied to the use of biological space probes with further investigatory research. Furthermore, from the biological screening results obtained, and the selectivity profile shown by these inhibitors, the synthesis of a second generation library of compounds is an additional research possibility. / AFRIKAANSE OPSOMMING: Kanker is die hoof oorsaak van sterftes ter wêreld, wat verantwoordelik is vir die dood van ongeveer 8.2 miljoen mense in die jaar 2012. Die siekte word geassosieer met twee geenfamilies, naamlik onkogene en gewasonderdrukkingsgene. Die kenmerke van kanker pathiogene behels geenversterking, puntmutasies of chromosomale herrangskikking binne in die gene. Kinase is verantwoordelik vir die omkeerbare fosforilering van proteine wat 'n uiters belangrike rol in sellulere sein transduksie speel. Abnormale kinase aktiwiteit lei tot ooruitdrukking, mutasies en chromosomale translokasie wat tot die ontwikkeling van onko- en gewasgroei en wat eindelik tot kanker lei. Deaktivering van die klas van ensieme is dus krities want dit sal die ongewenste abnormale aktiwiteite onderdruk. As gevolg van die bogenoemde, het navorsers kinase inhibeerders ontwikkel wat die spesifieke protein teiken en hiermee die sein transduksie roete asook gewas groei inhibeer. Hiermee het die sukses van inhibeerders veral die kommersiele inhibeerder, imatinib, grootliks toegeneem. Oor die afgelope jare het die belangstelling in die ontwikkeling van meer selektiewe en kragtige inhibeerders toegeneem as gevolg van die weerstand wat goedgekeurde terapeutiese middels opbou. In hierdie projek is daar gebruik gemaak van 'n C-C of C-N bindingsvorming strategie om bioaktiewe heterosikliese molekules te sintetiseer wat gekoppel is aan 1,2,3-triasool funksionele groepe. Die sintetiese metode maak gebruik van Sonogashira reaksies vir die 3-bromo-kwinolien, 7-chloro-4-iodokwinolien, 4-bromoisokwinolien en 5-bromoisokwinolien met trimetielsilielasetileen (TMSA), gevolg met die ontskerming van die TMS-groep om die terminale alkyn op die heterosiklusse te ontbloot. Die asied fragmente, bensiel asied en 2-(asidometiel)piridien, was toe gesintetiseer om met die gevormde heterosiklus alkyne 'n koper ondersteunende kliek chemie te ondergaan. 'n Reeks van 1,4-digesubstitueerde 1,2,3-triasool gebaseerde omkeerbare kinase inhibitore is toe gevorm. 'n Tweede reeks met o-, m-, en p- gesubtitueerde nitro bensiel asiede was gesintetiseer om 1,4- en 1,5- digesubtitueerde 1,2,3-triasole te sintetiseer met behulp van koper- en ruthenium ondersteunende kliek chemie. Laastens was die o-, m-, en p- nitro groepe gereduseer om 'n primêre amien te vorm. Die gevormende amien het 'n asileringsreaksie met akriloïel chloried ondergaan om die kern, die Michael akseptor, te inkorporeer. Die Michael akseptor word benodig om 'n onomkeerbare inhibitoriese aktiwiteit te kan uitvoer. Die projek het dus met behulp van kliek chemie, twee 1,2,3-triasool reekse gelewer wat omkeerbare en onomkeerbare inhibitoriese aktiwiteit kan uitvoer. Die verbindings gesintetiseerd in hierdie projek het keuringstoetse ondergaan teen die wilde tipe en teen twee gemuteerde forme van die EGFR kinase ensiem. Van hierdie verbindings het goeie selektiwiteit vertoon teenoor die gemuteerde EGFR kinase ensiem. Die mees aktiewe inhibeerder, N-{2-{[4-isokwinolin-4-iel)-1H-1,2,3-triasool-1-iel]feniel}akrielamied, het aktiwiteit in die lae μM reeks vertoon. Dié inhibisie waarde is vergelykbaar met die FDA goedgekeurde medikasie, gefitinib. In hierdie projek is sintetiese metodes ontwikkel wat toegepas kan word op meer intensiewe biologiese ondersoeke en asook meer navorsing. Die resultate vekry van die biologiese aktiwiteit, asook die verbindings se selektiwiteit, gee die moontlikheid vir die ontwikkeling en sintese van 'n tweede generasie verbindings.

Species composition, distribution, habitat preference of click beetle detected in Lithuanian agrocenoses, their need for certain soil properties and as well as food ration has not been yet fully explored in Lithuania. Every year, farmers suffer huge losses in relation to damage caused by click beetle larvae. They injure germinating seeds of the variety of plants, seedlings, underground parts of the plants, tubers, and roots. Damaged seeds do not sprout up, seedlings perish, and crops become sparse. The trade value gets worse and fungal or bacterial infection pervades through the injuries into potato tubers or vegetables during the storage period and finally the stored production gets rotten. There is a lack of data concerning click beetle bioecology and harmfulness under Lithuanian environmental conditions. In order to increase the efficacy of plant protection measures against these pests it is necessary to establish prevalent click beetle species composition, to explore their bioecological characteristics and the level of harm in agrocenoses under Lithuanian agroclimatic conditions. On the other hand, not every click beetle species is herbivorous and makes damage. There are species which are recognized as predators. In this respect, they may be eligible as natural enemies of pests for an integrated pest management approach. / Spragšiai (Elateridae) yra viena iš gausiausių rūšimis vabalų (Coleoptera) būrio, įvairiaėdžių (Polyphaga) pobūrio šeimų. Pasaulio vabalų faunoje yra aprašyta daugiau kaip 12000 spragšių rūšių priklausančių 600 genčių (Tarnawski, Buchholz, 2008). Vabalų si-stematikoje spragšių šeima priklauso stambiai spragšinių (Elateroidea) antšeimiui jungian-čiai ir kitas giminingas vabalų šeimas, tokias kaip: blusvabaliai (Throscidae), medienvaba-liai (Eucnemidae), Cerophytidae, Cebrionidae (dviejų pastarųjų šeimų atstovai Lietuvoje neaptinkami). Visi šio antšeimio vabalų suaugėliai turi charakteringą krūtinės sandarą: prieškrūtinėlės galiniame krašte yra smaili išauga (dantelis), kuri įsistato į specialią duobu-tę vidukrūtinėlės priekiniame krašte. Vabalui lankstant prieškrūtinį minėtas dantelis yra iš-traukiamas ir įstumiamas į vidukrūtinėlės duobutę su charakteringu spragtelėjimu, o tuo metu susidariusi atatrankos jėga mesteli visą vabalo kūną aukštyn, jei šis guli ant nugaros (Parker, Howard, 2001). Lietuvos spragšių fauna nėra pakankamai ištirta. Paskutiniame Lietuvos vabalų kata-loge, kuriame susumuota visa prieinama faunistinė informacija apie Lietuvos vabalus nu-rodyta, kad šiuo metu yra užregistruota 74 spragšių rūšys, o 30 rūšių yra pateikiamos kaip tikėtinos respublikos teritorijoje (Tamutis ir kt., 2011). Dar mažiau ištirtos blusvabalių ir medienvabalių šeimos, aptikta tik 22 – 42% visų tikėtinų rūšių. Daugumos spragšių rūšių vystymosi ciklas lervos tarpsnyje trunka nuo 2... [toliau žr. visą tekstą]

Pagrindinis šio darbo tikslas buvo susintetinti vandenyje tirpius norimos struktūros bei skirtingo pakeitimo laipsnio skiepytuosius chitozano-polietilenglikolio (MPEG) kopolimerus bei katijonizuotus chitozano darinius ir ištirti jų savybes. „Klik“ chemijos reakcijų pagalba susintetinti nauji įvairaus pakeitimo laipsnio chitozano-MPEG skiepytieji kopolimerai, turintys triazolilliekaną. Pasiūlyti nauji chitozano-C(6)-MPEG bei N-2,3-epoksipropil-N,N,N-trimetilamonio chloridu C(6)-katijonizuoto chitozano sintezės būdai, chitozano aminogrupių apsaugai naudojant chitozano kompleksus su dodecilsulfatu. Dalinai N-katijonizuoto chitozano darinius papildomai katijonizuojant šarminėje terpėje, gauti N,O-katijonizuoti chitozano dariniai, turintys labai didelį katijonizavimo laipsnį. Pasiūlytas katijonizuoto chitozano fermentinės hidrolizės metodas, kurį naudojant chitozano darinio molekulinę masę lengvai galima sumažinti dešimtimis kartų. Chitozaną modifikuojant vyno, citrinų, adipo rūgštimis, susintetinti dalinai tinklinti chitozano dariniai. Prie chitozano ir karboksirūgštimis modifikuotų chitozano nanodalelių prijungus (4-cianpentano rūgšties)-4-ditiobenzenkarboksilatą, susintetintas makroiniciatorius gyvybingajai radikalinei polimerizacijai RAFT metodu. / The main aim of this work was to synthesize water-soluble chitosan-methoxy poly(ethylene glycol) (MPEG) graft copolymers and quaternized derivative of chitosans of various structure and desirable graft density and to study their properties. Novel chitosan-MPEG derivatives containing triazolyl moiety with different degree of substitution of chitosan were prepared for the first time by “click chemistry”. Several new schemes of the synthesis of chitosan-C(6)-TMPEG and C(6)-quaternized chitosan derivatives were suggested based on protection of amino functionality by using chitosan-dodecyl sulfate complexes. Additional cationization of cationic chitosan through its hydroxyl groups in alkaline medium enabled to prepare N,O-quaternized chitosans derivatives with very high degree of quaternization. It was suggested method of enzymatic hydrolysis of quaternized chitosans which allow a tenfold decrease the molecular weight of chitosans derivatives. Modification of chitosan by tartaric, citric or adipic acid yielded partially crosslinked chitosan derivatives. Modification of chitosan and further modification of chitosan nanoparticles by dithiobenzendicarboxylate resulted in RAFT macroinitiators which are precursors of functionalized nanoparticles.

The main aim of this work was to synthesize water-soluble chitosan – methoxy poly(ethylene glycol) (MPEG) graft copolymers and cationized chitosan derivatives of various structure and desirable graft density, and to study their properties. Novel chitosan-MPEG derivatives with different degree of substitution of chitosan were prepared for the first time by “click” chemistry. Several new schemes of the synthesis of chitosan-MPEG and additionally cationized chitosan derivatives were suggested based on protection of amino functionality by using chitosan-dodecyl sulphate complexes. Additional cationization of chitosan through its hydroxyl groups in alkaline medium enabled to prepare chitosan derivatives with very high charge density. A method of enzymatic hydrolysis of the cationized chitosans was proposed which allowed a tenfold decrease of the molecular weight of chitosan derivatives. Modification of chitosan by tartaric, citric or adipic acid yielded chitosan nanoparticles. Further modification of chitosan nanoparticles by dithiobenzendicarboxylate resulted in RAFT macroinitiators used as precursors of functionalized nanoparticles. / Pagrindinis šio darbo tikslas buvo susintetinti vandenyje tirpius norimos struktūros bei pakeitimo laipsnio skiepytuosius chitozano – polietilenglikolio (MPEG) kopolimerus bei katijonizuotus chitozano darinius ir ištirti jų savybes. Įvairaus pakeitimo laipsnio chitozano-MPEG skiepytieji kopolimerai susintetinti vykdant „klik“ chemijos reakcijas. Pasiūlyti nauji chitozano-MPEG bei papildomai katijonizuoto chitozano sintezės būdai, chitozano aminogrupių apsaugai naudojant chitozano kompleksus su dodecilsulfatu. Dalinai katijonizuoto chitozano darinius papildomai katijonizuojant šarminėje terpėje, gauti chitozano dariniai, turintys labai didelį krūvio tankį. Pasiūlytas katijonizuoto chitozano fermentinės hidrolizės metodas, kurį naudojant chitozano darinio molekulinę masę lengvai galima sumažinti dešimtimis kartų. Chitozaną modifikuojant vyno, citrinų arba adipo rūgštimis, susintetintos nanodalelės. Prie chitozano nanodalelių prijungus (4-cianpentano rūgšties)-4-ditiobenzenkarboksilatą, susintetintas makroiniciatorius gyvybingajai radikalinei polimerizacijai RAFT metodu.

Glycans are macromolecules that contain several classes. Glycans can play an important role in biological activities. Studying the cell surface glycans can provide a very powerful way to understand the fundamental process. Also it could help to regulate expected cell response. Thus it is very necessary to have a method to detect cell- surface glycans efficiently. An efficient method for glycan detection is necessary. Metabolic glycan labeling and chemoenzymatic glycan labeling are most commonly used. Chemoenzymatic glycan labeling is a rapid and sensitive method which also has high specificity. This method can be applied in both vitro and vivo. However the availability of unnatural sugar nucleotides functioned by bioorthogonal groups is the main limitation for chemoenzymatic labeling. In this thesis, UDP-GlcNAc and UDP-GalNAc derivatives were prepared for further chemoenzymatic labeling by using chemoenzymatic synthesis method.

Click chemistry is a very powerful chemical strategy that overcome carbon-carbon bond with carbon-heteroatom bond by joining small units with heteroatom links (C-X-C) using spring-loaded reactants. The Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition is a major example based on the click chemistry philosophy. This method was used for the last 10 years to join different functional groups, carbohydrates, aminoacids, polymers to calix[4]arene and resorcin[4]arene cavitands by a stable 1,2,3-triazole linkages. Herein I describe our interest in this type of click chemistry reaction in the synthesis of dimeric capsules resorcin[4]arene via four 1,2,3-triazole linkages. Two different resorcin[4]arene derivatives were synthesized in which four azide and four alkyne functional groups were attached on the upper rim of two different resorcin[4]arenes. The dimerization reaction was quite challenging due to steric factors. Each resorcin[4]arene derivative was then studied individually via click chemistry and all click reaction results were excellent and the products were isolated in good yields. These results enhanced the synthesis of the dimeric resorcin[4]arene.

Depuis quelques années on assiste au développement de nouveaux bio-catalyseurs qui sont des hybrides combinant les avantages de la catalyse organométallique (système robustes, efficaces, mais couteux) à ceux de la catalyse enzymatique (écologique, spécifique mais peu flexible). Parmi les différentes stratégies mises en œuvre pour créer des enzymes artificielles, aucune d'elles n'a jusqu'à présent véritablement envisagé d'utiliser l'activité d'une enzyme et de la combiner à celle d'un composé organique. C'est la nouvelle approche proposée dans ce travail pour tenter d'orienter l'activité catalytique d'une oxydase à fort potentiel industriel, la laccase. Les produits d'oxydation de la laccase sont des radicaux phénoxyls qui se recombinent dans le milieu sans contrôle de l'enzyme. Chez certaines plantes, des petites protéines nommées « dirigent proteins » interagissent avec les radicaux phénoxyls pour conduire à la formation d'un seul produit optiquement pur. Dans ce travail, nous avons tenté de mimer ces « dirigent proteins » en greffant une molécule cage de type cyclodextrine à proximité du site actif de la laccase. Dans un premier temps, nous avons réalisé la synthèse de modules organiques dits « plateformes » possédants a) un point d'attachement à l'enzyme, b) un groupement pour la purification des protéines fonctionnalisées et c) une cyclodextrine qui permet d'encapsuler un grand nombre de molécules organiques. Par des mesures de fluorescences et d'immuno-détection, nous avons identifié les conditions optimales de fonctionnalisation pour la laccase et ainsi validé sa dérivatisation. / In recent years we are witnessing the development of new bio-catalysts which are hybrids combining the advantages of organometallic catalysis (robust and efficient system, but expensive) to those of enzymatic catalysis (ecological, specific but not very flexible). Among the various strategies used to create artificial enzymes, none of them has yet seriously considered to combine an enzyme activity with that of an organic compound. This is the new approach proposed in this work to try to orient the catalytic activity of the laccase, an oxidase with an industrial potential. The oxidation products of the laccase are phénoxy radicals which recombine in the medium regardless of the activity of the enzyme. In some plants, small proteins called "dirigent proteins" interact with phénoxy radicals leading to the formation of a single optically pure product. In this work, we tried to mimic the "dirigent proteins" by grafting a cyclodextrin-cage molecule near the active site of the laccase. As a first step, we performed the synthesis of organic modules called "platforms" with a) an anchor point to the enzyme, b) a group for functionalized protein purification c) a cyclodextrin that encapsulates a large number of organic molecules. By fluorescence and immunodetection measurements, we identified the optimal conditions for laccase functionalization and thus validated its derivatization. Monitoring the oxidation of coniferyl alcohol by the functionalized laccase with a cyclodextrined platform highlights a change in the kinetic profiles of the substrate and products. This difference appears due to the location of the cyclodextrin near the substrate oxidation site.