LIMA, Marcos Ferreira da Costa, também é conhecido em citações bibliográficas por: COSTA LIMA, Marcos / Submitted by Pedro Barros (pedro.silvabarros@ufpe.br) on 2018-08-17T21:44:49Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Carolliny Wanderley de Macedo.pdf: 1496616 bytes, checksum: 2b5f4861d50547eca06473ae0c8741bc (MD5) / Approved for entry into archive by Alice Araujo (alice.caraujo@ufpe.br) on 2018-08-24T22:43:43Z (GMT) No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Carolliny Wanderley de Macedo.pdf: 1496616 bytes, checksum: 2b5f4861d50547eca06473ae0c8741bc (MD5) / Made available in DSpace on 2018-08-24T22:43:43Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Carolliny Wanderley de Macedo.pdf: 1496616 bytes, checksum: 2b5f4861d50547eca06473ae0c8741bc (MD5) Previous issue date: 2017-07-11 / CAPES / Mudanças institucionais na área da Ciência, Tecnologia e Inovação (CT&I) vêm marcando as últimas décadas. Um dos resultados se refere à constante busca por um ambiente institucional que integre instituições de ensino superior e pesquisa, setor produtivo e governo no desenvolvimento de projetos e iniciativas inovadoras que busquem estimular o desenvolvimento socioeconômico, seja a nível nacional, regional ou local. Neste sentido, a partir de um estudo de caso sobre o Porto Digital do Recife, tem-se como objetivo analisar as interações entre o Centro de Informática da Universidade Federal de Pernambuco (CIn- UFPE), as empresas do setor de Tecnologia da Informação e Comunicação (TIC) e o governo, mais especificamente, o estadual e municipal. Para tanto, o referencial teórico concentra-se, sobretudo, nos modelos do Triângulo de Sábato e da Hélice Tríplice. Metodologicamente, foi realizado um estudo de caso qualitativo fundamentado, principalmente, em entrevistas e documentos, no qual a partir das etapas propostas por Bardin (1977) no método da análise de conteúdo e da utilização do programa Nvivo busca-se se identificar os fatores limitadores e facilitadores existentes nestas interações. A análise dos dados da pesquisa demonstra que apesar dos resultados positivos encontrados, as interações entre universidade, empresa e governo ainda não ocorrem de forma totalmente integrada, como indica o modelo equilibrado da Hélice Tríplice. No entanto, complementarmente, os resultados também indicam que, em termos gerais não se trata apenas de um problema específico do Porto Digital, como também reflete as dificuldades estruturais da CT&I no Brasil. / Institutional changes in the area of the Science, Technology and Innovation (ST&I) are marking the last decades. One of the results refers to the constant search for an institutional environment that integrates institutions of higher education and research, industry and government into the development of projects and innovative initiatives that look for stimulate the socioeconomic development, be at national, regional or local level. Thereby, from a case study on Porto Digital the aim is to analyze the interactions among the Centre of Informatics of the Federal University of Pernambuco (CIn-UFPE), the information and communication technologies' companies (ICT), and government. For this, The theoretical reference focuses mainly on the models of the Sabato Triangle and the Triple Helix. Methodologically, a qualitative case study was carried out, based on interviews and documents, in which from the stages proposed by Bardin (1977) in the method of content analysis and the use of the Nvivo program seek to identify the factors that hinder and facilitate these interactions. The data analysis shows that despite the positive results found, the university-companies-government interactions still do not occur in a fully integrated way as indicated by the balanced model of the Triple Helix. However, in addition, the results also indicate that, in general terms, this is not only a specific problem of the Porto Digital, but also reflects the structural difficulties of the ST&I’s policy in Brazil.

O propósito desta tese é investigar como a gestão do conhecimento e a colaboração universidade-empresa-governo incluindo as três hélices se relacionam influenciando o desempenho das organizações. Como principal contribuição, pretende-se propor um modelo analítico que relaciona as teorias da Gestão do Conhecimento e da Tripla Hélice, modelo mais referenciado para aprofundar esse tipo de cooperação, e as dimensões propostas (que são a estrutural, a relacional, a cognitiva e o contexto), considerando as particularidades do contexto brasileiro. No ambiente competitivo contemporâneo, a capacidade de as organizações criarem e utilizarem o conhecimento torna-se cada vez mais fundamental para a busca da vantagem competitiva sustentável, o que leva inclusive à busca de novas formas de arranjos interorganizacionais. A escolha do tema se justifica pela escassez de pesquisas empíricas que relacionem os tópicos de gestão do conhecimento e de colaboração universidade-empresa-governo de forma integrada com foco no contexto brasileiro. Os representantes desse tipo de colaboração selecionados para compor o estudo são Institutos Nacionais de Ciência e Tecnologia (INCTs). Como técnica qualitativa de análise de dados foi utilizada a análise de conteúdo categorial. Os principais resultados mostram que a estrutura organizacional (estrutural) influencia tanto o relacionamento entre os integrantes (relacional) quanto o fluxo de conhecimento (cognitiva), bem como os elementos relacionais (cultura colaborativa, confiança e liderança) facilitam o compartilhamento de conhecimento. Além disso, o contexto afeta essas três outras dimensões. Como principais barreiras no processo de transferência de conhecimento são identificadas as diferenças culturais, a burocracia e a realidade socioeconômica, e como facilitadores a presença de parques tecnológicos e incubadoras, a proximidade geográfica entre universidade e empresa e os incentivos governamentais. / This thesis focuses on an investigation into the way knowledge management and university-industry-government collaboration influence the performance of organizations. As the main contribution, an analytical model that relates the theories of Knowledge Management and the Triple Helix, the most referenced model for such cooperation, and the structural, relational, cognitive dimensions, as well as the context is proposed. The model takes into consideration the particularities of the Brazilian context. In todays competitive environment, the ability of organizations to create and use their knowledge has become fundamental for their pursuit of sustainable competitive advantages and new forms of organizational arrangements. The choice of the topic is justified by the scarcity of studies on the identification and analyses of the main aspects of this form of collaboration in an integrated way and focused on the Brazilian context. A categorical content analysis was used as a qualitative technique applied for a multiple case study of National Institutes of Science and Technology (INCTs). The results show both context and organizational structure (structural dimension) influence the relationship between members (relational dimension) and flow of knowledge (cognitive dimension) and the relational elements (collaborative culture, trust and leadership) facilitate knowledge sharing. Cultural differences, bureaucracy and socioeconomic reality were identified as the main barriers in the process of knowledge transfer, whereas facilitators included presence of science parks and incubators, geographical proximity between university and business and government incentives.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-08-24T19:24:23Z No. of bitstreams: 1 inaiaracosersobrinho.pdf: 1426545 bytes, checksum: 55114c9f9b21705eba3b5315ee786256 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-25T12:04:45Z (GMT) No. of bitstreams: 1 inaiaracosersobrinho.pdf: 1426545 bytes, checksum: 55114c9f9b21705eba3b5315ee786256 (MD5) / Made available in DSpace on 2017-08-25T12:04:45Z (GMT). No. of bitstreams: 1 inaiaracosersobrinho.pdf: 1426545 bytes, checksum: 55114c9f9b21705eba3b5315ee786256 (MD5) Previous issue date: 2017-07-11 / Devido à natureza evolucionária do sistema econômico, as mudanças de paradigmas induzem aos padrões de crescimento chamados de ondas longas. Essas mudanças, que ocorrem em média a cada 50 anos, são ocasionadas pela inserção de inovações disruptivas que revolucionam incessantemente a estrutura econômica, destruindo o antigo e criando novos elementos, não apenas a nível econômico, mas institucional, organizacional e social. Na década de 90, com o desenvolvimento da microeletrônica e das tecnologias de comunicações, emergiu o paradigma da tecnologia da informação, caracterizado pela intensidade de informação que, transformada em conhecimento e inovação, desempenha um papel crucial para desenvolvimento. Entretanto, para que isso ocorra, é necessário que os países construam arranjos institucionais apropriados. Com isso, surge o modelo de sistemas de inovação da Tríplice Hélice. Este modelo compreende a inovação e o progresso técnico, numa Economia do Conhecimento, como o resultado de um conjunto complexo de relações entre universidade-empresa-governo, atores diretamente envolvidos na produção, distribuição e aplicação do conhecimento. Neste contexto, o presente estudo teve o objetivo de identificar o impacto da produção de conhecimento e das políticas públicas para a produção de depósitos de patentes dos pesquisadores pertencentes ao domínio científico Ciências da Vida e da Saúde, das universidades federais mineiras. A análise considerou o período de 1995 a 2016. Para isso, foram utilizadas as técnicas de análise exploratória dos dados e de análise em painel. Os resultados mostraram que fatores educacionais (orientações em pós-graduação), econômicos (produtos tecnológicos e prestação de serviços tecnológicos) e políticos (arcabouço legal, recursos financeiros e políticas de estímulo) impactaram a produção de depósitos de patentes dos pesquisadores pertencentes ao domínio científico Ciências da Vida e da Saúde das universidades federais mineiras. A experiência acadêmica e o conhecimento científico, principal insumo para gerar inovação, não foram determinantes para a produção de depósitos de patente. Já os fatores políticos apresentaram um forte impacto, tanto na produção de conhecimento quanto nos depósitos de patente. Isso demonstra os esforços do Governo para tentar diminuir o hiato tecnológico. / Due to the evolutionary nature of the economic system, paradigm shifts induce the growth patterns called long waves. These changes, which occur on average every 50 years, are brought about by the insertion of disruptive innovations that unceasingly revolutionize the economic structure, destroying the old and creating new elements, not only at an economic but institutional, organizational and social level. In the 1990s, with the development of microelectronics and communications technologies, the paradigm of information technology emerged, characterized by the intensity of information that, transformed into knowledge and innovation, plays a crucial role in development. However, to trigger this process, countries need to build appropriate institutional arrangements. Appears, with it, the model of systems of innovation of the Triple Helix. This model comprises innovation and technical progress in a Knowledge Economy as the result of a complex set of relations between university-business-government. Being these the actors that are directly involved in the production, distribution, and application of knowledge. In this context, the present study aimed to identify the impact of the production of knowledge and public policies to produce patent deposits of researchers from the scientific field of Life Sciences and Health, from the federal universities of Minas Gerais. The analysis considered the period from 1995 to 2016. For this, the techniques of exploratory data analysis and panel data analysis were used. The results showed that educational factors (post-graduation orientations), economic (technological products and technological services provision) and political (legal framework, financial resources, and stimulus policies) impact the production of patent deposits of researchers belonging to the scientific domain Life Sciences and Health of the federal universities of Minas Gerais. Academic experience and scientific knowledge, the main input to generate innovation, were not decisive to produce patent deposits. On the other hand, the political factors had a strong impact, both in the production of knowledge and in patent deposits. This demonstrates the efforts of the Government to try to reduce the technology gap.

Orientadores: Roberto Antonio Clemente, Munemasa Machida / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-19T20:53:40Z (GMT). No. of bitstreams: 1 Duarte_ViniciusNjaim_M.pdf: 5509797 bytes, checksum: 163bd7750aa0326f7bf0d0b521dc88f0 (MD5) Previous issue date: 2012 / Resumo: Entre os diferentes métodos alternativos à indução, para sustentação e/ou geração de corrente em plasmas confinados magneticamente, com o objetivo de se obter o funcionamento contínuo de um possível reator de fusão, foi estudado aquele associado a campos magnéticos viajantes produzidos por bobinas helicoidais alimentadas por correntes de radiofrequência defasadas (double helix current drive). O método permite compensar as perdas de caráter resistivo em configurações toroidais de plasma, como os pinches de campo reverso (reversed field pinches - RFP). O problema pode ser reduzido ao estudo dos estados estacionários de uma coluna de plasma sujeita a campos de radiofrequência produzidos por bobinas helicoidais externas. Desprezando efeitos de gradientes de densidade e temperatura, o modelo é regido por um sistema de equações diferenciais ordinárias de segunda ordem não lineares acopladas, reguladas por quatro parâmetros adimensionais de interesse físico, que foram resolvidas numericamente usando o programa Mathematica. Estudou-se a eficiência do método em relação às aplicações em RFP, para os quais o campo magnético longitudinal apresenta uma inversão no interior da coluna de plasma. Isso implicou considerar regiões ainda não bem exploradas para os parâmetros de interesse. Os resultados numéricos são apresentados para configurações de campos magnéticos com simetria dipolar e quadrupolar / Abstract: Among the different methods, alternative to induction, to drive current in magnetically confined plasmas, with aim to obtain a continuous operation of a possible fusion reactor, we have studied the one associated to traveling magnetic field produced by helicoidal coils carrying out of phase radiofrequency currents (double helix current drive). The method allows compensating resistive losses in toroidal plasma configurations, like reversed field pinches. The problem may be reduced to the study of stationary states for a plasma column subjected to radiofrequency fields produced by external helicoidal coils. Neglecting density and temperature gradients, the model is governed by a system of coupled nonlinear second order ordinary differential equations, which depend on four dimensionless parameters of physical interest and can be solved numerically using the software Mathematica. We studied the efficiency of the method with respect to applications in reversed field pinches, for which the longitudinal steady magnetic field shows an inversion inside the plasma column. This implied considering not yet well explored regions of the parameters of interest. Numerical results are presented for magnetic field configurations of dipolar and quadrupolar simmetries / Mestrado / Física / Mestre em Física

L'omniprésence du collagène dans le corps humain et les nombreuses pathologies qui sont associées à ses anomalies de structure en font un objet d'étude de premier plan. Le collagène possède dans sa séquence primaire de nombreux cycles pyrrolidines stabilisant une structure secondaire de type polyproline II (PPII) et une structure tertiaire en triple hélice correspondant à un superenroulement de trois chaines peptidiques. Lors de ce travail, nous nous sommes intéressés à la synthèse et la caractérisation structurale de peptides mimes de collagène (CMP), seuls ou en présence de collagène de type I. Pour appréhender les différents niveaux de structuration des CMP: conformation locale, structures secondaires, assemblages trimériques et supramoléculaires, nous avons privilégié une approche muti-échelle. Les études que nous avons menées par dichroïsme circulaire et RMN ont visé à analyser en détail les relations entre triples hélices et les différentes espèces monomériques présentes en solution. Grâce à l'utilisation de peptides modèles marqués, nous avons pu mesurer par RMN des paramètres structuraux locaux et les comparer à des simulations de dynamique moléculaire. La présence d'assemblages supramoléculaires a été mise en évidence et analysé d'un point de vue qualitatif, quantitatif et cinétique par des études de DLS, RMN et par différentes approches de microscopies. Enfin, l'ensemble de nos observations nous ont conduit à proposer de nouvelles molécules CMP. Nous avons ainsi entrepris la synthèse de peptidomimétiques fluorés en vue d'améliorer la cinétique de formation et la stabilité de la triple hélice et pour également favoriser des assemblages supramoléculaires ordonnés. / The collagen is omnipresent in the human body and many diseases are associated with its structural anomalies, these are the main reasons to study its stability. Collagen has in its primary sequence many pyrrolidine cycles, which stabilize a secondary structure such polyproline II (PPII), and a triple helix structure where three left-handed helical polypeptide chains are supercoiled. In this work, we focused on the synthesis and structural characterization of collagen model peptides (CMP), alone or in the presence of type I collagen. To understand the different levels of CMP structuration: local conformation, secondary structures, trimeric and supramolecular assemblies, we favoured a multi-scale approach. The studies we conducted by circular dichroism and NMR aimed to analyze the relationship between triple helices and the different monomeric species present in solution. Through the use of labeled peptides models, we were able to measure NMR local structural parameters and compare them to molecular dynamics simulations. The presence of supramolecular assemblies was demonstrated and analyzed from a qualitative, quantitative and kinectics point of view by DLS, NMR and different microscopies approaches. Finally, all of our observations have led us to propose new CMP molecules. We undertook the synthesis of fluorinated peptidomimetics to improve the kinetics formation and stability of the triple helix, and also promote ordered supramolecular assemblies.

Le 26RFa est un neuropeptide de la famille des RFamide initialement isolé à partir d’un extrait de cerveaux de grenouille par notre laboratoire grâce à des anticorps dirigés contre le motif Arg-Phe-NH2 du NPFF de boeuf. Simultanément, deux laboratoires pharmaceutiques ont identifié le GPR103, un récepteur couplé aux protéines G jusque là orphelin, comme étant le récepteur de ce neuropeptide. Depuis, le GPR103 a été renommé QRFPR pour Pyroglutamylated RFamide peptide receptor. L’ADNc du pro-26RFa a été cloné chez différentes espèces, de l’amphioxus Branchiostoma floridae jusqu’à l’homme, ce qui a permis d’identifier dans le précurseur plusieurs sites de clivage potentiels par les prohormone convertases susceptibles de générer, outre le 26RFa, une forme allongée en N-terminal, le 43RFa aussi dénommé QRFP, et un peptide situé à l’extrémité C-terminale des 26RFa et 43RFa, le 26RFa(20-26), dont la séquence (GGFSFRF-NH2) est hautement conservée des amphibiens aux mammifères. Des expériences menées in vivo ou ex vivo chez le rongeur ont montré que le 26RFa et/ou le QRFP augmentent de façon dose-dépendante la consommation de nourriture, stimulent la sécrétion de gonadotropines et d’aldostérone et modulent la libération d’insuline induite par le glucose. Par ailleurs, l’invalidation du gène codant le QRFPR chez la souris provoque une ostéoporose sévère. L’ensemble de ces données indique que le 26RFa pourrait exercer diverses activités biologiques chez les vertébrés telles que le contrôle de la prise alimentaire, de l’insulinémie, de la reproduction, de l’homéostasie hydrominérale et de l’ostéogenèse. Enfin, il avait été montré précédemment que le 26RFa(20-26) mime les effets orexigèniques, insulinostatiques et hypophysiotropes du peptide de référence. Dans le cadre de cette thèse, nous nous sommes fixés comme objectifs de répondre aux questions suivantes (1) quel est l’impact de la variation de la longueur de la chaîne et de l’alkylation de la fonction guanidinium de l’Arg25 du 26RFa(20-26) sur l’activation du QRFPR ? (2) quel est l’effet d’analogues remarquables du 26RFa humain sur la prise alimentaire et l’homéostasie glucidique chez la souris ? et (3) la boucle extracellulaire reliant les domaines transmembranaires 4 et 5 (ECL2) du QRFPR présente-t-elle réellement une hélice-α dans le récepteur in cellulo et est-elle capable d’interagir avec l’hélice-α du 26RFa ? / 26RFa is a neuropeptide of the RFamide family, originally isolated from a frog brain extract by using antibodies raised against the Arg-Phe-NH2 motif. Concomitantly, two pharmaceutical companies have shown that 26RFa is the endogenous ligand of the former orphan G protein-coupled receptor GPR103 now renamed QRFPR. Analysis of the human 26RFa precursor indicates that pre-pro26RFa may generate several additional peptides including an N-terminally extended form (43RFa) and a truncated peptide 26RFa(20-26) (GGFSFRF-NH2) which is strictly conserved in mammals. In rodents, 26RFa and 43RFa induce a dose dependent increase in food intake, stimulate secretion of gonadotropins and aldosterone, as well as modulating glucose-induced insulin release. Furthermore, QRFPR-knockout mice suffer from osteopenia and exhibit the characteristic kyphotic hump of osteoporotic patients. Altogether these data indicate that 26RFa may exert diverse biological activities in vertebrates such as food intake control, reproduction and osteogenesis. It is important to note that the Cterminal heptapeptide, 26RFa(20-26), mimics the orexigenic and gonadotropic effects of 26RFa. The purpose of the present study was (1) to determine the impact of Arg25-modified 26RFa(20-26) analogues on the activation of the QRFPR (2) to evaluate the effect of remarkable analogues of hQRFPR, in vivo in a food intake and glucose homeostasis paradigm (3) to evaluate if the second extracellular loop (ECL2) of the QRFPR really presents a short α-helix and is able to interact with 26RFa α-helix?

Ces travaux de thèse s'inscrivent dans un projet à long terme concernant le développement de nouvelles réactions de contraction de cycle originales afin d'accéder à des édifices moléculaires organisés à activités biologiques potentielles. Généralement découvertes de manière fortuite, les réactions de contraction de cycle sont des réarrangements offrant l'avantage de modifier rapidement le squelette des molécules et permettant donc un accès facile à des analogues structurels, une propriété intéressante et utile aussi bien en chimie de synthèse qu'en chimie médicinale. Dans cette optique, trois réactions de contraction de cycle différentes ainsi que leurs applications seront rapportées dans ce manuscrit. La première décrit la réactivité particulière des bis-Boc 2,5-dicétopipérazines (DKPs) en milieu basique et leur conversion en hydantoïnes, deux squelettes hétérocycliques d'intérêt pharmacologique. Ce nouveau réarrangement a été appliqué à différentes DKPs avec des rendements satisfaisants et de bons excès énantio- ou diastéréoiso-mériques. L'intérêt des bis-Boc DKPs en tant que plateforme de départ dans la construction de structures complexes a ensuite été démontré lors de l'obtention de spirolactames grâce à l'utilisation de la réaction de réarrangement transannulaire de lactames activés (TRAL) et la mise au point d'une stratégie de cyclisation rapide et efficace. Après dimérisation de ces bicycles, les études par dichroïsme circulaire, RMN et modélisation moléculaire ont mis en évidence un comportement similaire à celui d'hélices de polyproline II (PPII), des structures peptidiques secondaires largement impliquées dans les interactions protéine-protéine et dans des processus pathogènes. Afin de valider le potentiel de mimes de nos dimères, une fonctionnalisation de ces substrats s'est avérée nécessaire, qui a été en partie réalisée grâce à la découverte d'une nouvelle réaction de contraction de cycle. Effectuée à chaud dans plusieurs solvants et en présence d'un catalyseur de type triflate, ce réarrangement permet la conversion de quelques bicycles accolés en spirocycles avec de bons rendements. L'intérêt de ces travaux réside ainsi sur l'utilisation de 2,5-dicétopipérazines activées comme substrat de départ et démontre la gamme d'applications multiples des réactions de contraction de cycle.

Ces travaux de thèse s'inscrivent dans un projet à long terme concernant le développement de nouvelles réactions de contraction de cycle originales afin d'accéder à des édifices moléculaires organisés à activités biologiques potentielles. Généralement découvertes de manière fortuite, les réactions de contraction de cycle sont des réarrangements offrant l'avantage de modifier rapidement le squelette des molécules et permettant donc un accès facile à des analogues structurels, une propriété intéressante et utile aussi bien en chimie de synthèse qu'en chimie médicinale. Dans cette optique, trois réactions de contraction de cycle différentes ainsi que leurs applications seront rapportées dans ce manuscrit. La première décrit la réactivité particulière des bis-Boc 2,5-dicétopipérazines (DKPs) en milieu basique et leur conversion en hydantoïnes, deux squelettes hétérocycliques d'intérêt pharmacologique. Ce nouveau réarrangement a été appliqué à différentes DKPs avec des rendements satisfaisants et de bons excès énantio- ou diastéréoiso-mériques. L'intérêt des bis-Boc DKPs en tant que plateforme de départ dans la construction de structures complexes a ensuite été démontré lors de l'obtention de spirolactames grâce à l'utilisation de la réaction de réarrangement transannulaire de lactames activés (TRAL) et la mise au point d'une stratégie de cyclisation rapide et efficace. Après dimérisation de ces bicycles, les études par dichroïsme circulaire, RMN et modélisation moléculaire ont mis en évidence un comportement similaire à celui d'hélices de polyproline II (PPII), des structures peptidiques secondaires largement impliquées dans les interactions protéine-protéine et dans des processus pathogènes. Afin de valider le potentiel de mimes de nos dimères, une fonctionnalisation de ces substrats s'est avérée nécessaire, qui a été en partie réalisée grâce à la découverte d'une nouvelle réaction de contraction de cycle. Effectuée à chaud dans plusieurs solvants et en présence d'un catalyseur de type triflate, ce réarrangement permet la conversion de quelques bicycles accolés en spirocycles avec de bons rendements. L'intérêt de ces travaux réside ainsi sur l'utilisation de 2,5-dicétopipérazines activées comme substrat de départ et démontre la gamme d'applications multiples des réactions de contraction de cycle. / This work is part of a long-term project aiming to develop new and original ring contraction reactions to access organised molecular edifices with potential biological activities. Ring contraction reactions are usually discovered in a fortuitous manner and present the advantage of rapid and efficient modifications of the molecular skeletons, allowing thus an easy access to structural analogues, a useful and interesting property both in terms of synthetic and medicinal chemistry. With this aim in mind, three different ring contraction reactions, as well as their uses, are reported in this manuscript. The first one describes the particular reactivity of bis-Boc 2,5-diketopiperazines (DKPs) in a basic medium and their conversion into hydantoins, two heterocyclic skeletons with pharmacological interest. This new rearrangement has been applied to several DKPs with acceptable yields and good enantio- or -diasteroiso-meric excesses. The interest of bis-Boc DKPs as starting platforms for the construction of complex structures has later been demonstrated with the obtaining of spirolactams thanks to the use of the transannular rearrangement of activated lactams (TRAL) reaction followed by a fast and efficient ring-synthesis strategy. The studies by circular dichroism, NMR and molecular modelling performed after the dimerisation of those bicycles showed a similar behaviour to the one of polyproline II (PPII) helix, a secondary peptidic structure involved in protein-protein interactions and in pathogenic processes. A functionalization of our dimer then turned out to be necessary in order to validate the mimic potential of our dimers, which was done in part thanks to the discovery a new ring contraction reaction. In the presence of a triflate catalyst in various solvents under high temperatures this rearrangement allows a clean conversion of some fused bicycles into spirocycles with good yields. The interest of this work thus lies in the use of activated 2,5-diketopiperazines as starting materials and demonstrates the wide range of applications of ring contraction reactions.

La communication entre les différentes organelles se fait par l’intermédiaire du trafic vésiculaire, un processus qui nécessite un remodelage continu des membranes. Les vésicules fortement courbées bourgeonnent d'un compartiment donneur et fusionnent avec un compartiment accepteur. Les protéines impliquées dans le bourgeonnement et fusion des vésicules ont été largement étudiées. Récemment, la découverte de détecteurs de courbure membranaire a révélé que le trafic membranaire pourrait être régulé à un niveau supplémentaire, par la détection de la forme de la membrane. Le premier détecteur de courbure membranaire identifié était le motif ALPS (Amphipathic Lipid Packing Sensor), qui a été trouvé dans un certain nombre de protéines de la voie sécrétoire précoce et l'enveloppe nucléaire. La protéine d’arrimage GMAP-210 localisé au niveau du cis-Golgi, est composée d’une longue superhélice (coiled-coil) et d’un motif ALPS à l'extrême N-terminale. Il a été démontré in vitro, que ce motif se replie et forme une hélice amphipathique capable de se fixer sur des petits liposomes. Toutefois, l'identité des vésicules, reconnues par ce détecteur de courbure dans la cellule, reste inconnue. α-Synucléine est une autre protéine qui se lie préférentiellement à des membranes très courbées. Cette protéine localisée sur les vésicules synaptiques, est impliquée dans la régulation du taux de vésicules au niveau des terminaisons nerveuses pré-synaptiques. Connue pour son rôle central dans le développement de la maladie de Parkinson, α-synucléine contient une région non structurée en solution, mais qui forme une hélice amphipathique au contact de petits liposomes in vitro. Les hélices amphipathiques formées par le motif ALPS et α-synucléine sont très différentes aussi bien sur le plan chimique que sur le plan conformationel. Le motif ALPS possède une face hydrophobe bien développée, mais un coté polair pauvre avec très peu de résidus chargés. α-Synucléine, en revanche, a un côté hydrophobe modéré, et une face polaire zwitterionique riche en résidus chargés. L'objectif principal du projet était de comparer les propriétés de liaison aux membranaires in vivo et in vitro de ces deux hélices amphipathiques de structure opposée. L’expression de ces deux sondes chez la levure, favorise l'accumulation de structures vésiculaires de propriétés différentes. L'extrémité N-terminale de la protéine GMAP-210 contenant son motif ALPS (GMAPN) co-localisé spécifiquement avec des marqueurs de la voie sécrétoire précoce, alors une sonde contenant une portion de l’hélice amphipathique d’α-synucléine co-localise avec des marqueurs endocytiques et post-Golgiens. La mutagenèse du motif ALPS et l'inversion de la séquence de ALPS dans GMAPN confirment que ce détecteur de courbure membranaire se fixe spécifiquement aux vésicules via des interactions directes protéines-lipides, plutôt que les interactions protéines-protéines. Notre analyse a montré que ces détecteurs de courbure mammifères, exprimés dans la levure préservent leur capacité à cibler des vésicules spécifiques, vésicules de la voie sécrétoire précoce pour les motifs ALPS, et vésicules d’endocytose/post-Golgi pour α-synucléine. La composition membranaire de ces vésicules correspond à la composition des liposomes fixés par le motif ALPS et α-synucléine in vitro. Les propriétés biochimiques opposées du motif ALPS et α-synucléine, sont parfaitement adaptés à chacun de ces deux environnements membranaires dans la cellule. Le programme HeliQuest est conçu pour identifier des hélices amphipathiques capables de se lier sur les membranes, y compris les motifs ALPS. Un nouveau module conçu pour identifier les hélices amphipathiques avec des propriétés similaires à α-synucléine a été récemment élaboré. Les recherches effectuées dans les bases de données de protéines de levure et humaines ont permis d’identifier des hélices amphipathiques candidats qui ont des propriétés similaires à α-synucléine, dans de nombreuses protéines. Nous avons préparé un ensemble de sondes, dans lequel ces hélices sont insérées à la fin de la superhélice de GMAPN. Une première étude de leur co-localisation dans les cellules de levure avec un ensemble de marqueurs démontre une localisation spécifique, ce qui suggère que ces hélices peuvent avoir la capacité de cibler des membranes de manière spécifique. D'autres travaux seraient nécessaires pour confirmer ou pas si ces hélices amphipathiques font partie d'une nouvelle classe de détecteurs de courbure ayant les mêmes propriétés que α-synucléine. / Communication between membrane-bound organelles is mediated by vesicular trafficking, a process which requires continual membrane remodeling. Highly curved vesicles bud from a donor compartment through functioning of different coat protein complexes, and fuse with an acceptor compartment thanks to proteins of the membrane fusion machinery. The proteins involved in vesicle budding and fusion have been extensively studied. Recently, the discovery of membrane curvature sensors revealed that membrane trafficking could be regulated at an additional level, through detection of the shape of a membrane. The first membrane curvature sensor identified was the ALPS (Amphipathic Lipid Packing Sensor) motif, which has been found in a number of proteins that function in the early secretory pathway and nuclear envelope. One example is GMAP-210, a long coiled-coil tether localizing to cis-Golgi membranes, which has an ALPS motif at its extreme N-terminus. This ALPS motif was found to fold into an amphipathic helix and bind to small liposomes in vitro. However, the identity of the vesicles that this curvature sensor binds to in cells is not known. Another protein - α-synuclein - has also been reported to bind preferentially to highly curved membranes. This neuronal protein localizes to synaptic vesicles and is involved in maintaining the reserve pool of vesicles in pre-synaptic nerve terminals. α-Synuclein, known for its central role in the development of Parkinson’s disease, contains a region that is unstructured in solution, but forms an amphipathic helix upon binding to small liposomes in vitro. The chemistry and geometry of the amphipathic helices formed by ALPS motifs and α-synuclein are very different. The ALPS motif has a well-developed hydrophobic face but a poor polar side with few charged residues. α-Synuclein, in contrast, has a restrained hydrophobic side, and a zwitterionic polar face rich in charged residues. The main goal of the project was to compare the in vivo and in vitro membrane binding properties of these two amphipathic helices of opposite structure. When expressed in yeast cells, these two curvature sensors promoted the accumulation of vesicular structures possessing different characteristics. The N-terminus of GMAP-210 containing its ALPS motif (GMAPN) co-localized specifically with early secretory pathway markers, whereas a probe containing a portion of the amphipathic membrane-binding helix of α-synuclein co-localized with endocytic and post-Golgi markers. Mutagenesis of the ALPS motif and the inversion of the ALPS sequence in GMAPN support the conclusion that this membrane curvature sensor is targeted to specific vesicles in cells through direct protein-lipid, rather than protein-protein interactions. Our analysis has shown, remarkably, that mammalian curvature sensors expressed in yeast cells preserve their capacity to target specific vesicles, those of the early secretory pathway for ALPS motifs, and endocytic/post-Golgi vesicles for α-synuclein. The membrane composition of these vesicles corresponds to the preferred in vitro liposome binding properties of these membrane curvature sensors. The contrasting chemistries of ALPS motifs and α-synuclein are well adapted to each of these two major membrane environments in the cell. The HeliQuest algorithm is designed to search databases for membrane-binding amphipathic helices, including ALPS motifs. A new module designed to identify amphipathic helices with properties similar to α-synuclein has recently been developed. Searches of both yeast and human protein databases has identified candidate α-synuclein-like amphipathic helices in numerous proteins. We prepared a set of probes, in which these helices are displayed at the end of the GMAPN coiled-coil. An initial study of their co-localization in yeast cells with a set of organelle markers demonstrates specific localization patterns, suggesting that these helices may have specific membrane targeting capacities. Further work will explore the question of whether these amphipathic helices are part of a novel class of α-synuclein-like curvature sensors.

Este trabalho tem como objetivo auxiliar os institutos de pesquisa, notadamente o IPEN, a melhorar a assertividade do processo de definição de suas linhas de pesquisa. Novas velocidades evolutivas que aumentam exponencialmente exigem maior sincronia e ação múltipla e coordenada dos três elementos fundamentais para o desenvolvimento das sociedades contemporâneas: o governo, a estrutura produtiva e a infra-estrutura científica e tecnológica. Esse ambiente cada vez mais dinâmico e mutante impõe uma maior proximidade com o meio socioeconômico que passa de cliente-consumidor à do co-criador do conhecimento e fornecedor de energia agora contida em um novo padrão de relações sociais, denominado Sociedade em Rede. A diferença nos tempos da Universidade, da Estrutura Produtiva e do Governo é função do tempo de suas atividades centrais: a Ciência, o Mercado e a conquista da Opinião Pública, respectivamente. A equação que harmoniza e encontra sinergias entre as três dimensões é o desafio contemporâneo daqueles que procuram inovar e avançar no conhecimento em prol da sociedade. Neste trabalho procura-se mostrar que a saída para os institutos de pesquisa está em acreditar na frase de Robert Plomin e procurar conectar-se ao diferentes elos das cadeias para fazer uso de uma inteligência coletiva que se expande em velocidade e qualidade superiores a qualquer outro momento na história da humanidade. A comparação dos resultados obtidos com a aplicação de diferentes metodologias de análise permite mostrar os pontos fortes e pontos de atenção, ameaças e oportunidades do IPEN fornecendo subsídios para encontrar o melhor modo para adequar seu desempenho às novas demandas. / This work aims to assist research institutes, notably the IPEN, in order to improve their assertiveness in the process of defining their research lines. New evolutionary speeds have increased exponentially requiring greater synchronism and multiple and coordinated action from the three fundamental elements in order to assure the development of the contemporary society: Government, Productive Structure and Infrastructure in Science and Technology. This environment increasingly dynamic and mutant imposes greater proximity with the socioeconomic environment when former client-consumer has become the co-creator of knowledge and supplier of energy now contained in a new standard of social relations, called Networked Society. The difference in time for the University, the Productive Structure and Government is function of its main activities: Science, Market and the achievement of Public Opinion, respectively. The equation that will harmonize and find synergies between these three dimensions is the contemporary challenge for those who seek to innovate and advance knowledge in order to improve the standard of living of the society. In this work is shown that research institutes must believe in the words of Robert Plomin and start connecting to the several links in different chains in order to make use of a collective intelligence that continuously expands in speed and quality higher than in any other time in human history. The comparison among the results obtained from the different methodologies of analysis proposed in this work allows finding out strengths and weaknesses, threats and opportunities of the IPEN providing subsidies in order to find better ways to tailor its performance to the new demands.