A presente dissertação trata do estudo experimental do comportamento estrutural de barras helicoidais assentadas sobre superfície cilíndrica e sujeitas a cargas de compressão. Aparato experimental específico foi projetado e construído para este fim. O projeto, bem como a aferição deste aparato, é descrito em detalhes. Este aparato permite ajustar as barras através de um sistema de apoios constituídos por uma série de rolamentos, que podem ser posicionados de forma a conferir liberdade de deslocamento à barra em duas direções distintas: radial (normal à superfície cilíndrica de assentamento) e lateral (tangencial; bi-normal). A aplicação de carga compressiva se faz na direção tangencial à hélice não-deformada. Barras com seção transversal circular e retangular, com diversos comprimentos livres de flambagem e para diferentes ângulos de assentamento, foram ensaiadas. Estudos preliminares, com barras retas, permitiram avaliar as condições efetivas de engastamento proporcionadas pelo aparato. Nestes casos foi possível induzir o fenômeno de flambagem, recuperando-se, consistentemente, os valores de cargas críticas previstas pela teoria de Euler e avaliando-se o grau de engastamento proporcionado pelo aparato experimental. Filmagem com câmera de alta velocidade permitiu observar o fenômeno de instabilidade. O comportamento estrutural das barras curvas, de seção circular e retangular, foi então estudado. Tanto o comprimento livre quanto o ângulo de assentamento foi variado. O estudo permitiu levantar base de dados experimentais do comportamento de barras helicoidais nessas condições de carregamento e de condições de contorno. No entanto, para nenhuma das diversas condições ensaiadas foi possível induzir o fenômeno de instabilidade. Tal fato poderia dar subsídios a inferências acerca do estudo da instabilidade de tubos flexíveis do tipo birdcaging. / This dissertation deals with an experimental study on the structural behavior of bars supported on a helical cylindrical surface and subject to compressive loads. A special experimental apparatus was designed and built for this purpose. The design, as well as the adjustment of such an apparatus is described in details. The device allows one adjusting the bars by using a system consisting of a series of bearings that can be positioned to give freedom to the structure in two different directions: radial (normal to the cylindrical surface) and lateral (tangential or bi-normal). The compressive load is applied in the tangential direction of the helix. Bars with circular and rectangular cross sections, with various buckling lengths and different helix angles, were tested. Preliminary studies with straight bars, have allowed to evaluate the boundary conditions offered by the apparatus. In these cases, it was possible to induce the phenomenon of buckling, obtaining, consistently, the values of critical loads provided by the theory of Euler and to evaluate the boundary conditions provided by the apparatus. The use of a high-speed camera allowed to observe the phenomenon of instability. The structural behavior of curved bars of circular and rectangular sections was also studied. Both, the test free length as the helix angle were varied. The study enabled us to get a huge amount of experimental data about the behavior of helical bars, subjected such loading and boundary conditions. However, the phenomenon of instability could not be induced, for any condition tested. This fact could collaborate for further inferences about the study of the birdcaging instability at flexible pipes.

A classe de proteínas das MEGs (codificadas por genes de micro-éxon) presente em Schistosoma mansoni, ganhou evidência após a publicação do genoma deste parasita, principalmente por ser majoritariamente secretada, estando em contato direito com moléculas do hospedeiro, e possuir alta taxa de variação, o que poderia ter relação com um possível um mecanismo de evasão do sistema imune. Assim, foram escolhidas proteínas da classe das MEGs, todas com predição de hélice anfipática em sua estrutura, para investigação neste trabalho. Hélices anfipáticas são amplamente descritas na literatura como tendo alta propensão à interação com membranas celulares e interessantes funções fisiológicas. O objetivo deste projeto foi estudar a dinâmica de interação com membranas e estabelecer possíveis indícios de função biológica das proteínas MEG-24 e MEG-27 a partir de técnicas biofísicas. Optou-se por trabalhar com essas proteínas produzidas a partir da síntese química. Utilizando as técnicas de CD, Fluorescência e DLS, observou-se que a presença de miméticos de membrana induzem o enovelamento e o aumento da estabilidade térmica de MEG-27, e interferem no seu estado oligomérico. Para MEG-24, também foi observado aumento da estabilidade térmica e influência no estado oligomérico na presença de sistemas miméticos de membrana. Utilizando OCD, inferiu-se que MEG-27 possivelmente interage com a superfície da membrana, a passo que MEG-24 se insere na bicamada. Adicionalmente, ambas foram capazes de interferir na dinâmica de vesículas, conforme observado pelo ensaio de vazamento de calceína e DSC. Utilizando células de eritrócito e um modelo de membrana a partir dessas células (ghosts) foram realizados ensaios biológicos, DSC e EPR. A capacidade de MEG-24 e MEG-27 realizarem hemólise e hemoaglutinação, respectivamente, reitera o potencial de interação destas proteínas com membranas biológicas. Os resultados de DSC apontaram que ambas interferem nas transições das proteínas de membrana embebidas na bicamada de ghosts de eritrócitos. Por EPR, notou-se que MEG-27 tem maior efeito na dinâmica de lipídios em detrimento a MEG-24, possivelmente devido a um mecanismo de acomodação envolvendo domínios raft e a diferença de orientação de interação entre ambas as proteínas. A expressão de MEG-27 exclusivamente na região da glândula do esôfago em vermes adultos verificada por WISH, sugere que a mesma deva entrar em contato com células recém ingeridas pelo parasita. Não foi observada atividade antimicrobiana para ambas e não foram encontrados parceiros de interação proteínas pela técnica de Duplo-híbrido para MEG-27. Concluiu-se que os peptídeos estudados interagem com membranas biológicas, podendo ter papéis importantes na interface de interação parasito-hospedeiro. / The class of MEGs proteins (coded by micro-exon genes) present in Schistosoma mansoni, drawn attention after the parasite genome publication. This proteins are mostly secreted, being in direct contact with host molecules and with a high rate of variation, which could be a mechanism of Imune system evasion. Thus, proteins of the MEGs class, all with amphipathic prediction in their structure, were chosen for investigation in this work. Amphipathic helices are widely described in the literature with high propensity to interact with membranes and, consequently, probability of related biological function. The objective of this project was to study the interaction dynamics with membranes and to establish possible indications of biological function of MEG-24 and MEG-27 proteins from biophysical techniques. We chose to work with these proteins produced by chemical synthesis. Using CD, Fluorescence and DLS techniques, it was observed that the presence of membrane mimetics induced the folding and increased thermal stability of MEG-27, and interfered with its oligomeric state. For MEG-24, an increase in thermal stability and influence on the oligomeric state was also observed when in the presence of membrane mimetic systems. The results of OCD suggest that MEG-27 possibly interacts with the membrane surface, whereas MEG-24 is inserted into the bilayer. Both were able to interfere with vesicle dynamics, as observed by the Leakage and DSC tests. Using a more realistic membrane model from erythrocyte cells, biological assays, DSC and EPR were performed. The ability of MEG-24 and MEG-27 to perform hemolysis and hemagglutination, respectively, provides evidence of the potential for interaction of these proteins with biological membranes. The DSC results indicated that both interfere with the transitions of the membrane proteins embedded in the bilayer of erythrocyte ghosts. By EPR, it was noted that MEG-27 has a greater effect on lipid dynamics than MEG-24, possibly due to an accommodation mechanism involving raft domains and the difference in orientation of interaction between both proteins. The expression of MEG-27 exclusively in the region of the esophagus gland in adult worms verified by WISH suggests that it should come into contact with cells just ingested by the parasite. No antimicrobial activity was observed for both and no protein interaction partners were found by the MEG-27 double-hybrid technique. It was concluded that the studied peptides interact with biological membranes and may have important roles in the parasite-host interaction interface.

Increased interaction between scientists and the social environment is considered to be one of the characteristics of modern science. This interaction can occur through collaboration between different sectors in society. In connection to this, the Triple Helix model claims that interaction between university, industry and public sectors, is key to modern innovation development. So far, cross-sector interaction between actors in environmental science has been scarcely studied in a scientific manner. Most studies carried out in the area have disregarded the actual practice of such collaborations and what happens in projects where these sectors interact. As this has become a common way to solve environmental problems, it is of considerable importance to gain more knowledge about this process. The objective of this research was to study and explain cross-sector collaboration. Using the interactive research method, characterised by joint learning and interaction with the participants, this was explored through two case studies. The method was well suited for studying ongoing interactions between the university, industry and public sectors. The first case was an international collaboration between representatives of the Triple Helix sectors. Here, olive-mill wastewater in Greece was the focus. The Triple Helix framework was used both on the intended analytical level and at a management level closer to the actor level of the participants. The second case was a three-year environmental research project in the Kalmar region where strong university-industry collaboration was carried out in order to find wastewater treatment solutions in the wood industry. This collaboration was extended to include more actors in the region during the process. The actual practice of these cases showed the importance of a dialogue between participants. Triple Helix can be used as an initial framework for such a dialogue through which the model is redefined by input from all sectors.

Esta pesquisa realiza um estudo da relação entre universidades-centros de pesquisa e empresas no setor de biomateriais, no estado do Paraná (Brasil). Os dados foram levantados por meio de entrevistas exploratórias realizadas com onze líderes de grupos de pesquisa, com representantes dos setores de pesquisa e desenvolvimento de quatro empresas ligadas ao setor de biomateriais e com os responsáveis pelos Núcleos de Inovação Tecnológica das universidades contempladas pela pesquisa. Os resultados das entrevistas com os pesquisadores mostram as motivações para o estabelecimento das parcerias, as principais dificuldades, bem como as lacunas que dificultam o avanço das pesquisas no estado. As entrevistas exploratórias com os representantes das empresas identificaram as motivações para o estabelecimento das parcerias, as formas utilizadas para identificar os pesquisadores, as principais dificuldades, bem como as principais lacunas nesta relação. Foi realizada também uma pesquisa bibliográfica a respeito dos mecanismos governamentais de apoio, na qual foram levantadas as principais legislações federais sobre o processo de inovação, as legislações locais e os principais mecanismos de subvenção atuantes no estado. Por fim, foram identificadas e analisadas as boas práticas implantadas pelas empresas e universidades-centros de pesquisa. Este trabalho finaliza com a apresentação de dois protocolos de boas práticas disponibilizados para empresas e instituições de pesquisa, e um protocolo de ações para o governo, com o objetivo de aprimorar esta relação, tão importante para o desenvolvimento científico-tecnológico no país. / This research conducts a study of the interaction between universities-research centers and companies on the biomaterials industry in the state of Paraná (Brazil). Data were collected through exploratory interviews with eleven leaders of research groups, with representatives of research and development areas of four companies linked to the biomaterials sector and with those responsible for Technological Innovation Centers in universities covered by this study. The results of the interviews with the researchers show the motivations for the establishment of partnerships, the main difficulties, as well as the gaps that hinder the progress of research in the state. The exploratory interviews with representatives of companies identified the motivations for the establishment of partnerships, the ways used to identify the researchers, the main difficulties, as well as the main gaps in this regard. It was also performed a bibliographic research regarding government support mechanisms, in which were surveyed main federal laws about the process of innovation, local laws and the mechanisms of subvention in the state. Finally, were identified and analyzed the best practices implemented by companies and universities-research centers. This study concludes with the presentation of two protocols of best practices made available for companies and research institutions, and a protocol of suggestions to the government, aiming to improve these relations, so important to the scientific and technological development in this country.

No contexto de universidade empreendedora, as incubadoras de empresas são um locus onde se acolhe empreendedores apoiando-os para que seus projetos tornem-se realidade através da constituição de pequenas empresas. Estar no ambiente de uma incubadora universitária de empresas significa estar próximo à universidade e tendo facilitado e estimulado o acesso e colaboração com a Academia. Se poderia questionar que efeitos o processo de incubação provoca na universidade que mantém uma incubadora de empresas e; por outro lado, que vantagens uma empresa nascente teria em estabelecer-se dentro de uma incubadora. Para subsidiar a análise dessas questões, o objetivo da presente pesquisa é analisar as interações universidade- empresa, em empresas incubadas e graduadas, que ocorrem no âmbito de uma incubadora universitária de empresas. Foi estudado o ambiente de incubação da Incubadora de Empresas de Base Tecnológica da UNISINOS, conhecida por UNITEC, através de coleta de dados via questionário submetido às empresas que estavam residentes na Incubadora no ano de 2009. Este estudo foi conduzido do ponto de vista da empresa que passa pelo processo de incubação, materializado na visão de seu empreendedor, sendo respondido por 15 empreendedores que representam 15 das empresas incubadas e graduadas residentes. Os resultados obtidos permitiram identificar: as parcerias, a receita mensal regular das empresas incubadas, o baixo nível de endividamento, e a troca de informações técnicas com outras empresas, como efeitos do processo de incubação nas empresas. Também pemitiram identificar as palestras em sala de aula, as visitas de alunos nas empresas e a consultoria prestada por alunos, como principais efeitos na Universidade. Além disso, se pode identificar que as percepções dos executivos das empresas graduadas e incubadas, divergem na maioria das questões. / Considering the entrepreneurship university context, the business incubators are a kind of locus that holds entrepreneurs, helping them to make their projects come true via the establishment of small companies. Being inside university business incubator means to have easy access and stimulated collaboration with the University. It could be asked which effects the incubation process brings to a university that holds a business incubator and, on the other hand, which advantages could be reached by a startup company settled inside an incubator. In order to support the analysis of these kinds of questions, the objective of this research is to analyze the interactions university-industry that occurs in a university business incubator. This study considers the incubation environment at UNISINOS University (located in the southern Brazil), called UNITEC, throw data collected using a questionnaire that was submitted to companies that were resident at UNITEC incubation environment at the year 2009. This whole study considers the point of view of 15 companies that were passed through incubation process, including incubated companies and also graduated ones. From the obtained results, it´s possible to indentify: the partnerships among resident companies, the recurring monthly income of incubated companies, the low level of indebtedness of all companies and, the technical information exchange among the companies, as effects from the incubation process in the resident companies. It´s also to indentify that the lectures by entrepreneurs at university classes, the students visits at companies and, consultancy services by students, as the main effects of the incubation process at the University. Besides that, it´s possible to realize that entrepreneurs from the incubated and graduated companies diverge in most questions.

Esta pesquisa realiza um estudo da relação entre universidades-centros de pesquisa e empresas no setor de biomateriais, no estado do Paraná (Brasil). Os dados foram levantados por meio de entrevistas exploratórias realizadas com onze líderes de grupos de pesquisa, com representantes dos setores de pesquisa e desenvolvimento de quatro empresas ligadas ao setor de biomateriais e com os responsáveis pelos Núcleos de Inovação Tecnológica das universidades contempladas pela pesquisa. Os resultados das entrevistas com os pesquisadores mostram as motivações para o estabelecimento das parcerias, as principais dificuldades, bem como as lacunas que dificultam o avanço das pesquisas no estado. As entrevistas exploratórias com os representantes das empresas identificaram as motivações para o estabelecimento das parcerias, as formas utilizadas para identificar os pesquisadores, as principais dificuldades, bem como as principais lacunas nesta relação. Foi realizada também uma pesquisa bibliográfica a respeito dos mecanismos governamentais de apoio, na qual foram levantadas as principais legislações federais sobre o processo de inovação, as legislações locais e os principais mecanismos de subvenção atuantes no estado. Por fim, foram identificadas e analisadas as boas práticas implantadas pelas empresas e universidades-centros de pesquisa. Este trabalho finaliza com a apresentação de dois protocolos de boas práticas disponibilizados para empresas e instituições de pesquisa, e um protocolo de ações para o governo, com o objetivo de aprimorar esta relação, tão importante para o desenvolvimento científico-tecnológico no país. / This research conducts a study of the interaction between universities-research centers and companies on the biomaterials industry in the state of Paraná (Brazil). Data were collected through exploratory interviews with eleven leaders of research groups, with representatives of research and development areas of four companies linked to the biomaterials sector and with those responsible for Technological Innovation Centers in universities covered by this study. The results of the interviews with the researchers show the motivations for the establishment of partnerships, the main difficulties, as well as the gaps that hinder the progress of research in the state. The exploratory interviews with representatives of companies identified the motivations for the establishment of partnerships, the ways used to identify the researchers, the main difficulties, as well as the main gaps in this regard. It was also performed a bibliographic research regarding government support mechanisms, in which were surveyed main federal laws about the process of innovation, local laws and the mechanisms of subvention in the state. Finally, were identified and analyzed the best practices implemented by companies and universities-research centers. This study concludes with the presentation of two protocols of best practices made available for companies and research institutions, and a protocol of suggestions to the government, aiming to improve these relations, so important to the scientific and technological development in this country.

Avec 8,8 millions de décès dénombrés en 2015, le cancer est l’une des plus grandes causes de mortalité dans le monde. De nouvelles stratégies thérapeutiques ont émergé et l’identification de nouvelles cibles biologiques comme notamment la protéine Asf1, un chaperon d’histone H3-H4 surexprimée dans les cellules cancéreuses et en particulier le cancer du sein. Cette protéine possède différentes fonctions dans la cellule et agit à plusieurs endroits par des interactions protéine-protéines. Au cours de cette thèse de doctorat, nous avons développé une stratégie originale de design d’inhibiteurs d’interactions protéine-protéine avec des foldamères peptidomimes à base d’urées. Ces foldamères ont 1) la capacité de se replier en hélice 2,5, rappelant les hélices α des peptides et 2) d’être hautement tolérés et initiateurs d’hélicité lorsqu’ils sont conjugués à des fragments peptidiques. Nous avons développé des oligomères mixtes comprenant une alternance de segment(s) peptidique(s) et multi-urée, appelées chimères, ayant l’avantage de combiner la reconnaissance naturelle de peptides et la forte propension des oligourées à former des hélices stables. Après une étude structurale montrant qu’avec l’insertion d’un court segment à base d’urées dans un peptide hydrosoluble adoptant une conformation en hélice  la conformation hélicoïdale pour une majorité des chimères est conservée, des composés mimant la partie hélicoïdale C-terminale de l’histone H3 ont été élaborés. Une interaction de l’ordre du micromolaire avec Asf1 a été observée en solution puis validée à l’état solide par cristallographie aux rayons X. En vue d’optimiser la reconnaissance de ces chimères avec la surface d’Asf1 et leur sélectivité, un panel de modifications a été réalisée (i.e. séquence primaire, longueur du segment urée). Nous avons ainsi conçu des chimères α/urée possédant des affinités de liaison pour Asf1 comprises entre le nano- et micromolaire. Le composé le plus prometteur a été internalisé avec succès dans des cellules cancéreuses après conjugaison bioreductible avec un peptide vecteur et pourrait conduire à la mort cellulaire de la lignée tumorale étudiée. / In 2015, 8.8 million of death were due to cancer making it an important cause of death in the world. The necessity to develop new anticancer treatments led to the search and discovery of new biological targets, such as Asf1, a histone chaperone protein of H3-H4 which is overexpressed in cancer cells, in particular in breast cancer. This protein plays a role in different biological processes in cells through protein-protein interactions (PPIs). During this thesis, we developed an original strategy to design inhibitors of PPIs with urea-based peptidomimetics. These foldamers are able to fold into stable 2.5-helix reminiscent to the natural α-helix. Designed urea-based foldamers have been synthesized as hybrid oligomers consisting of α-peptide and oligourea segments. With a combination of the two backbones, these compounds named “chimeras” presents advantages of both species with the natural recognition of α-peptides and the innate helical stability of oligourea. First, a model study was performed to evaluate the impact of the introduction of short urea segments into a long water-soluble peptide. Circular dichroism experiments confirmed that the helical conformation was conserved. New series of compounds that mimic a helical part of H3 were synthesized and their interaction with Asf1 was studied in solution and in solid state using a range of biophysical methods. Several modifications into the sequence were performed (side chain substitution, size of the urea segment or compound) in order to improve the recognition of Asf1 surface as well as their selectivity. We conceived oligourea-peptide chimeras with affinity for Asf1 in the micromolar range. Our best compound linked to a cell penetrating peptide was shown to enter into cells and to induce cell death.

Les gouttelettes lipidiques (GL) sont des organites intracellulaire qui jouent un rôle central dans le métabolisme des lipides. Elles sont également impliquées dans des maladies telles que l'obésité ou le diabète. Les GL ont une structure unique : une monocouche de phospholipides (PL) qui entoure un cœur de lipide neutre composé de triglycérides (TAG) et d'esters de cholestérol (CE). Certaines protéines sont recrutées sur les GL mais également à la surface d'autres organites, alors que d'autres protéines ciblent spécifiquement la surface des GL. Il a été montré que quelques une de ces protéines seraient sensibles à une haute tension de surface, soit une augmentation de l'aire par lipide, dans des GL reconstituées. Comment les propriétés de surface d'une GL diffèrent d'une membrane ? Comment la surface d'une GL répond à l'augmentation de la tension de surface ?Comment les protéines interagissent avec la surface des GL ? Nous avons réalisé des simulations de dynamique moléculaire atome-unifié de système tricouche qui mime la surface d'une GL afin de caractériser les propriétés de surface de cet organite. Plusieurs simulations ont été effectuées à différentes tension de surface en augmentant l'aire par lipide. Les propriétés de surface ont été caractérisées en terme de défauts de \textit{packing} (i.e. vides interfaciaux à l'interface membrane/eau). Aucune différence n'a été observé avec une bicouche à l'équilibre. Cependant, la tension de surface promeut l'insertion de lipides neutres dans la monocouche et augmente significativement les défauts de \textit{packing}. Des simulations préliminaires sur l'interaction d'une protéine modèle, la périlipine 4, qui se lie aux GLs \textit{in vivo} via une longue hélice amphipathique 11/3 ont été faites. Les premiers résultats montrent que la protéine adopte une structure plus flexible dans une interface huile/eau que dans une interface membrane/eau. Des essais de dimérisation montrent que la répartition des résidus chargés serait importante pour le processus d'oligomérisation. Pris globalement, ces résultats apportent une compréhension moléculaire quantitative sur l'effet de la tension de surface sur la monocouche de GL et des résultats préliminaires sur l'interaction protéine/GL. Notre travail constitue une première étape vers la description du comportement et de la structure des propriétés de surface des GL et peut être utile à la compréhension du ciblage protéique vers la surface de GL. / Lipid droplets (LD) are intracellular organelles that have a central role in lipid metabolism andimplication in diseases such as obesity and diabetes. LDs have a unique architecture: aphospholipid (PL) monolayer that surrounds a neutral lipid core composed of triacylglycerols (TAG)and cholesteryl esters (CE). Some proteins are recruited both to LDs and to other cellularorganelles, whereas others are targeted specifically to the surface of LDs. It has been shown thatsome of these proteins could be sensitive to a high surface tension (ST), increase in the area perlipid, in reconstituted LD. How do surface properties differ between a membrane and an LD? Howdoes the LD surface respond to an increase in ST? How do proteins interact with LDs? Weperformed united-atom molecular dynamics simulations on trilayer systems that mimic the LDsurface to investigate the surface properties of this organelle. Several simulations were performedat different ST by increasing the area per lipid. Surface properties were characterized in terms ofpacking defects (i.e interfacial voids at the membrane-water interface). No difference was observedwith a bilayer at equilibrium. However, high ST promoted the insertion of neutral lipids into themonolayer and a significant increase of packing defects. Preliminary simulations has been done oninteraction of a model protein called perilipin 4, which binds to LDs \textit{in vivo} using a long 11/3amphipathic helix. The first results show that the protein adopts a more flexible conformation on oilwaterinterface than in bilayer-water interface. Attempts of dimerisation show that the localization ofthe charged residues may be involved in the oligomerisation process. Taken together, our resultsprovide a quantitative molecular understanding of how ST affects the LD surface and preliminaryresults on protein-LD interaction. Our work constitutes a first step towards characterizing thebehavior and structure of LD surface properties and will be useful for a better understanding onhow some specific proteins are targeted to LD.

The protein-protein interactions (PPIs) occur when two or more proteins are bound together. Also, this protein-protein interactions (PPIs) cause the various biological processes in the body. Due to this reason, abilities of controlling or inhibiting PPIs can give us promising advantages like (1) better understanding of biological systems, (2) development of new diagnostic approaches for health or disease, and (3) establishment of novel molecular therapeutics. Many proteins adopt the secondary structures, where most of protein-protein interactions take place. -Helices and -sheets are the prevalent secondary conformations, but there are extended secondary structures such as -hairpins, -turns, 310 helix, and so on. As a result, construction of molecules mimicking these protein secondary structures is tractable target for drug design. Moreover, in drug discovery, designing peptidomimetics or non-peptidic mimetics is a popular strategy instead using peptides or truncated peptides because peptides or truncated peptides are prone to proteolysis and degraded in the body. Also, peptidomimetics and non-peptidic mimetics have not only the similar topology as peptides but also resistance to proteolysis. Due to these advantages, in this study, peptidomimetics or non-peptidic mimetics were synthesized and tested for different targets: (1) synthesis of non-peptidic -helical mimetics for p53-MDM2 inhibition, (2) solution-phase synthesis of -hairpin peptide for the inhibition of multiple myeloma cells (MM) adhesion, and (3) synthesis of -hairpin peptoid-peptide hybrids. The synthesis in all three different studies was succeeded, but they still need some improvements. For instance, non-peptidic -helical mimetics, terpyrimidyl derivatives, were synthesized successfully, but they did not show any bioactivity against p53-MDM2. Also, they have a solubility problem. Based on these results, it is necessary to improve the pharmacokinetic properties and bioactivity by changing the substituents on the rings or structures. The -hairpin peptide for the second case already showed good bioactivity against multiple myeloma (MM). For the next level of bio-study, the considerable amount of a -hairpin peptide was demanded. In order to make the substantial -hairpin peptide, the solution phase peptide synthesis was chosen instead of the solid phase peptide synthesis because of the cost-effect. Two methodology were tried for the solution-phase peptide synthesis: (1) segment ligation and (2) continuous synthesis. In the former case, the -hairpin peptide synthesis was successful, but, in the latter case, it is necessary to investigate the appropriate coupling reagents for each step. Peptoid-peptide hybrids has been one of the popular peptidomimetics in the last two decades. Also, mimicking the peptide secondary structure in peptoids has been studied extensively these days. The combination of these two factors was the goal for the third case. Because peptoid-peptide hybrids with a secondary structure can be recognizable by native proteins and resistant to proteolysis. So far, three sets of peptoid-peptide hybrids were synthesize and checked the secondary structure formation by using NMR. However, there was no indication of the secondary structure formation in the three sets of peptoid-peptide hybrids. This result suggests that it is necessary to introduce the more constrained components in peptoid-peptide hybrids. In the above three chapters, it has been tried to find the new drug candidates by synthesizing peptidomimetics or non-peptidic mimetics. Even though the synthesis was successful, some intended results such as the bioactivity or the secondary structure formation were not obtained. However, these results can give us the inspirations to improve properties of peptidomimetics or non-peptidic mimetics for a certain purpose, which leads to earn the intended results and eventually find new drug candidates.

cGMP-dependent protein kinases (PKG) are key players in intracellular second messenger signaling within many cellular systems throughout the body. Most notably PKG is known for its role in smooth muscle relaxation (Pfeiffer et.al, 1999). The Iα PKG isozyme has been identified as the primary effector of the nitric oxide pathway (and serves to be a novel drug target). To date the overall knowledge of structure and function of PKG is lacking in terms of the mechanisms of activation and the structural orientations that coordinate them. Recently, our laboratory has solved the crystal structure of the regulatory domain of PKG Iα, which revealed a previously unknown α-helical domain dubbed the Switch Helix (SW) (Osborne et.al, 2011). The SW domain was found to be a site of interprotomer communication via hydrophobic interactions between its C-terminus and hydrophobic residues, named the nest located on the opposing protomer. Synthetic peptides derived from the SW domain, named S-tides, dosedependently activate PKG Iα (Moon et.al, 2015). In addition, the amino acid residues of the nest are in proximity to the cGMP binding site B. It was hypothesized that the binding site for S-tides (nest) and the cGMP binding site B interact and are co-dependent of one another. The hypothesis of this thesis is the binding site for the S-tides (nest) and the cGMP binding site B interact and are co-dependent of one another. To test this hypothesis two aims were constructed: Aim 1: To develop an S1.5 analog that utilizes both the nest and the B-site to increase S-tide activity, Aim 2: To explore the intricacies of these modes of activation and how they interact with each other to obtain a better understanding of the interplay between these two sites. First, based on the most potent S-tide S1.5 (YEDAEAKAKYEAEAAFFANLKLSD, Ka=6 μM), two analogs were synthesized. The peptide S2.5 which lacked the amino acids LSD at the C-terminus showed a three-fold lower activation constant (Ka= 15 μM), although the molecule retained its helicity as demonstrated by circular dichroism. The second analog, S3.5 contained unnatural amino acid components from a molecular modeling approach in an effort to further increase the affinity by interacting with the adjacent cGMP binding site B. However, S3.5 showed further reduction in activity with an activation constant of 70 μM. These findings led us to conclude that the failure of the SAR approach indicates a different mode of S-tide activation as had been previously thought. Next, we investigated the role of the cGMP binding site B in the mechanism of S-tide mediated PKG Iα activation. Co-activation assays with cGMP and S1.5 demonstrated that cGMP activation is not altered in the presence of S1.5. Furthermore, S1.5 mediated activation is negatively affected in the presence of cGMP. These results suggest that the B-site of cGMP does not positively enforce the S1.5 activation kinetics. Next, we employed the PKG Iα mutant E292A, which cannot bind cGMP to the B-site (Moon et.al., 2018). Interestingly, this mutant retains the activation kinetics of PKG Iα WT when activated via S1.5 and cGMP. Thus, the cGMP binding site B is not crucial in the activation mechanisms of activating PKG Iα with cGMP. Likewise, the cGMP binding site B is not crucial in the activation mechanisms of activating PKG Iα with S1.5. To further support these findings, the PKG Iα mutant C42A, which showed crippled cGMP activation kinetics could be activated with S1.5 with a potency similar to wild type. Taken together, the results in this thesis demonstrate that in contrast to the initial hypothesis the binding sites for S-tides and cGMP, although in proximity, show no experimental support of a positive interaction. These findings are significant as they reveal that S1.5 mediated activation of PKG is truly independent of cGMP, thereby providing a molecular platform for the therapeutic development of these unique peptides.