Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-04-02T15:02:41Z No. of bitstreams: 1 AdrianaMarinaESilvaParente_DISSERT.pdf: 1386035 bytes, checksum: 87910526a122893f94a9f3045c8c9c4f (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-04-05T13:08:04Z (GMT) No. of bitstreams: 1 AdrianaMarinaESilvaParente_DISSERT.pdf: 1386035 bytes, checksum: 87910526a122893f94a9f3045c8c9c4f (MD5) / Made available in DSpace on 2018-04-05T13:08:05Z (GMT). No. of bitstreams: 1 AdrianaMarinaESilvaParente_DISSERT.pdf: 1386035 bytes, checksum: 87910526a122893f94a9f3045c8c9c4f (MD5) Previous issue date: 2017-11-28 / Tityus stigmurus corresponde ? esp?cie de escorpi?o predominante na regi?o Nordeste do Brasil, sendo considerado um dos principais causadores de acidentes escorpi?nicos. Na pe?onha do T. stigmurus, que ? composta de uma mistura complexa de mol?culas de alta e baixa massa molecular, foi identificado e caracterizado um pept?deo antimicrobiano denominado Stigmurina (FFSLIPSLVGGLISAFK-NH2). Pept?deos antimicrobianos s?o pequenas mol?culas consideradas a primeira linha de defesa contra micro-organismos, apresentando amplo espectro de a??o antimicrobiana. A literatura reporta tamb?m a atividade desses pept?deos contra c?lulas cancer?genas. Sequ?ncias nativas de pept?deos bioativos como prot?tipo para a obten??o de novas mol?culas t?m sido utilizadas com o intuito de potencializar a sua atividade e reduzir a toxicidade. Nesse contexto, realizou-se a caracteriza??o estrutural in silico e por dicro?smo circular, bem como a avalia??o da atividade antimicrobiana, antiparasit?ria, antiproliferativa e hemol?tica de dois pept?deos an?logos obtidos ? partir da Stigmurina, denominados StigA3 e StigA4. A an?lise da conforma??o tridimensional in silico do StigA3 e StigA4 demonstrou uma estrutura helicoidal, sendo este resultado confirmado por dicro?smo circular. O aumento da carga superficial e do momento hidrof?bico de ambos os pept?deos an?logos quando comparado com a Stigmurina resultaram na potencializa??o da atividade antimicrobiana e antiparasit?ria. Os pept?deos StigA3 e StigA4 apresentaram a??o antiproliferativa semelhante ao pept?deo nativo, com exce??o para a c?lula normal, para qual os pept?deos an?logos se mostraram menos t?xicos. Portanto, estes resultados indicam uma potencial aplica??o terap?utica destes pept?deos an?logos, demonstrando a efici?ncia do desenho racional de f?rmacos para a obten??o de novos agentes antiproliferativos e anti-infecciosos. / Tityus stigmurus it?s the predominant scorpion specie in Northeast region from Brazil, it?s considered one of the main cause of scorpion accidents in this region. In T. stigmurus venom, which is a complex mixture of high and low molecular mass molecules, was identified an antimicrobial peptide denominated Stigmurin. Antimicrobial peptides are small molecules considered the first line of defense against microorganisms, they show broad spectrum action. Many authors have proved that these peptides can also be effective on cancerous cells. Mutation in these molecules sequence has been held aiming the increase in the activity maintaining its low toxicity. Therefore, it is proposed the characterization of the structure in silico and by circular dichroism, as well the antimicrobial, antiparasitic, anti-proliferative and hemolytic activities of two analog peptides from Stigmurin, denominated StigA3 and StigA4. We performed an in silico analysis for these peptides, where we were able to observe ?-helix structure, which was confirmed by circular dichroism. We were also able to find that the analog peptides net charge and hydrophobic moment were higher than Sitgmurin?s, which can explain the increase in antimicrobial and antiparasitic activity. The peptides StigA3 e StigA4 showed activity on cancerous cells similiar to the native peptide, except when tested on a normal cell we were able to find that they?re less toxic. Therefore, these results indicate a potential biotechnological application for the analogs peptides, even as prototype to new therapeutic agents.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-02-13T19:44:50Z No. of bitstreams: 1 MenillaMariaAlvesDeMelo_DISSERT.pdf: 3756380 bytes, checksum: ee8b551187bf0b88e2a2414cc2bfa94e (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-02-14T21:18:32Z (GMT) No. of bitstreams: 1 MenillaMariaAlvesDeMelo_DISSERT.pdf: 3756380 bytes, checksum: ee8b551187bf0b88e2a2414cc2bfa94e (MD5) / Made available in DSpace on 2017-02-14T21:18:32Z (GMT). No. of bitstreams: 1 MenillaMariaAlvesDeMelo_DISSERT.pdf: 3756380 bytes, checksum: ee8b551187bf0b88e2a2414cc2bfa94e (MD5) Previous issue date: 2016-07-29 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Venenos de escorpi?es constituem uma rica fonte de pept?deos, que podem ser classificados como pept?deos com liga??es dissulfeto e pept?deos sem liga??es dissulfeto. Pept?deos ani?nicos correspondem aos componentes sem liga??es dissulfeto mais abundante na pe?onha do escorpi?o Tityus stigmurus (esp?cie prevalente no nordeste brasileiro), sendo ricos em res?duos de ?cidos asp?rtico e glut?mico. Esta abordagem apresenta, pela primeira vez, a caracteriza??o estrutural e a avalia??o da atividade biol?gica de um pept?deo ani?nico presente na pe?onha do escorpi?o Tityus stigmurus, denominado TanP. A estrutura tridimensional do TanP foi predita por modelagem computacional e refinada por simula??es de din?mica molecular, sendo a estrutura secund?ria obtida por dicro?smo circular, e estabilidade estrutural avaliada em diferentes meios, pH, temperatura e presen?a de ?ons cobre. Al?m disso, utilizou-se a espectroscopia UV-vis?vel para avaliar a atividade quelante de TanP na presen?a de cobre. As atividades antimicrobiana, citot?xica, imunomoduladora e antioxidante tamb?m foram avaliadas. As an?lises de CD indicaram uma predomin?ncia de conforma??o rand?mica em meio aquoso, bem como mudan?as estruturais dependentes de pH e temperatura. Os ?ons cobre, ao se ligarem ao pept?deo, modificaram a estrutura do mesmo. Tais dados corroboraram com o que foi demonstrado na din?mica molecular. A raz?o molar de liga??o (TanP:cobre) na din?mica molecular foi 1:5, enquanto no ensaio de reatividade observou-se raz?es de 1:7 e 1:3, a depender da concentra??o de TanP na solu??o. TanP n?o induziu citotoxicidade para as c?lulas normais e cancer?genas testadas, e apresentou capacidade de inibir, in vitro, a libera??o de ?xido n?trico por macr?fagos estimulados por LPS. Desta forma, os resultados sugerem que TanP ? um pept?deo promissor para aplica??o terap?utica como um agente quelante, bem como agente imunomodulador e antioxidante. / Scorpion venoms are a rich source of peptides, which may be classified as disulfide-bridged or non-disulfide-bridged peptides. Among them, there are anionic peptides, rich in aspartic and glutamic acid residues. Despite being the most abundant component in the venom gland of Tityus stigmurus (the prevalent scorpion species in Northeast Brazil), they are poorly characterized in the literature. This work presents, for the first time, structural characterization and biological activity assays of an anionic peptide from the venom of the scorpion T. stigmurus, named TanP. The three-dimensional structure of TanP was obtained by computational modeling and refined by molecular dynamic (MD) simulations. Furthermore, we have performed circular dichroism (CD) analysis to predict TanP secondary structure, and UV-visible spectroscopy to evaluate its chelating activity. CD indicated predominance of random coil conformation in aqueous medium, as well as changes in structure depending on pH and temperature. TanP has chelating activity on copper ions, which modified the peptide?s secondary structure. These results were corroborated by MD data. The molar ratio of binding (TanP:copper) depends on the concentration of peptide. TanP was not cytotoxic to normal or cancer cell lines, and showed an ability to inhibit the in vitro release of nitric oxide by LPS-stimulated macrophages. In this way, the results suggest TanP is a promising peptide for therapeutic application as a chelating, immunomodulatory and antioxidant agent.