Estudos das propriedades estruturais de análogos substituídos com 'TRP POT.2,7 ou 24' do fragmento com 30 resíduos da região amino-terminal da Esticolisina II
Carregando...
Data
2006-04-28
Autores
Crusca Junior, Edson [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Este trabalho descreve a sintese, a relacao estrutura-funcao, a interacao com membranas e a atividade biologica de um peptideo proveniente da regiao amino-terminal da proteina Esticolisina II (St II). Esta proteina e uma citolisina pertencente a familia das actinoporinas, obtida da anemona marinha Stichodactyla heliantus. Estudos estruturais e biologicos da proteina nativa indicam que a regiao amino-terminal da St II participa do processo de formacao de poros em membranas. Deste modo, visando compreender o comportamento e a importancia dessa regiao para a atividade biologica da St II, 3 analogos contendo os 30 primeiros residuos que compoem a extremidade amino-terminal da St II foram sintetizados e analisados. Os peptideos foram obtidos mediante sintese em fase solida modificando-se um residuo de leucina ou isoleucina por triptofano nas posicoes 2, 7 ou 24. Os estudos conformacionais foram realizados atraves das tecnicas de fluorescencia e dicroismo circular. Para avaliar o comportamento estrutural dos peptideos em solucao, foram realizados estudos de variacao de pH, forca ionica e titulacao com um agente indutor de estrutura, o trifluoroetanol (TFE). Na interacao com mimeticos de membranas, os peptideos foram titulados por tres tipos de detergentes: dodecil-sulfato de sodio (SDS), HPS (N-hexadecil-N,N-dimetil-3-amonio-1-propano-sulfonato) e LPC (1-palmitoil-2-hidroxi-sn-glicero-3- fosfocolina). Complementando o estudo acima, tambem foram realizados experimentos utilizando acrilamida como agente supressor de fluorescencia. Os resultados obtidos demonstram que a estrategia de sintese de peptideos em fase solida atraves do protocolo Fmoc/tBu, utilizada na sintese dos peptideos deste trabalho, foi viavel. O processo de purificacao dos peptideos atraves de HPLC tambem se mostrou eficiente e viabilizou a obtencao do material com alto indice de pureza.
In this study, we describe the synthesis, the relation function-structure, the interaction with membranes and the biological activity of the N-terminus region of the protein Sticholysin II (St II). This protein is a citolisin, which belongs to the family of the actinoporins, purified from the sea anemone Stichodactyla heliantus. According to biological and structural studies of the native protein, the N-terminus region of St II is involved on the pore formation process in membranes. In order to elucidate the function and the importance of this region to the biological activity of St II, three analogs containing the first 30 residues of the N-terminus region of St II were synthesized and analyzed. The peptides were obtained by solid phase synthesis and altered through the substitution of a leucine or isoleucine for a tryptophan on the positions 2, 7 and 24. Circular dichroism (CD) and tryptophan fluorescence studies have been carried out to investigate conformational properties of the peptides. In order to evaluate the structural modification on aqueous solution, studies were performed in order to evaluate the pH, ionic strength and addition of the secondary structural-inducing solvent TFE. The interaction studies with micelles were performed using three different surfactants: sodium dodecil-sulfate (SDS), N-hexadecyl-N,N-dimethyl-3-ammoniumpropanesulfonate (HPS) and lysophosphatidylcholine (LPC), and using acrylamide as a fluorescence suppression agent. We have demonstrated that on solid phase peptides synthesis using the Fmoc/tBu strategy is a success. The purification process of peptides through HPLC, has also revealed to be efficient, once the material was obtained with high purity level above 95%. The experiments of hemolytic activity showed that the three peptides have activities in æM concentration, this results reinforce the idea that the 30 residues of the N-terminus region have an important role on pore formation in membranes.
In this study, we describe the synthesis, the relation function-structure, the interaction with membranes and the biological activity of the N-terminus region of the protein Sticholysin II (St II). This protein is a citolisin, which belongs to the family of the actinoporins, purified from the sea anemone Stichodactyla heliantus. According to biological and structural studies of the native protein, the N-terminus region of St II is involved on the pore formation process in membranes. In order to elucidate the function and the importance of this region to the biological activity of St II, three analogs containing the first 30 residues of the N-terminus region of St II were synthesized and analyzed. The peptides were obtained by solid phase synthesis and altered through the substitution of a leucine or isoleucine for a tryptophan on the positions 2, 7 and 24. Circular dichroism (CD) and tryptophan fluorescence studies have been carried out to investigate conformational properties of the peptides. In order to evaluate the structural modification on aqueous solution, studies were performed in order to evaluate the pH, ionic strength and addition of the secondary structural-inducing solvent TFE. The interaction studies with micelles were performed using three different surfactants: sodium dodecil-sulfate (SDS), N-hexadecyl-N,N-dimethyl-3-ammoniumpropanesulfonate (HPS) and lysophosphatidylcholine (LPC), and using acrylamide as a fluorescence suppression agent. We have demonstrated that on solid phase peptides synthesis using the Fmoc/tBu strategy is a success. The purification process of peptides through HPLC, has also revealed to be efficient, once the material was obtained with high purity level above 95%. The experiments of hemolytic activity showed that the three peptides have activities in æM concentration, this results reinforce the idea that the 30 residues of the N-terminus region have an important role on pore formation in membranes.
Descrição
Palavras-chave
Peptídeos - Síntese, Fluorescencia, Dicroismo circular, Biotecnologia, Peptide synthesis, Fluorescence
Como citar
CRUSCA JUNIOR, Edson. Estudos das propriedades estruturais de análogos substituídos com 'TRP POT.2,7 ou 24' do fragmento com 30 resíduos da região amino-terminal da Esticolisina II. 2006. 99 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Química., 2006.