Estudo do potencial do peptídeo antimicrobiano ocelatina-Pt7 em permeabilizar membranas biomiméticas

• Autor(a) principal: Carvalho, Elizangela de Almeida [UNIFESP]
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UNIFESP
• Texto Completo: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=6514047; https://repositorio.unifesp.br/handle/11600/53042
• topic: Antimicrobial peptides; Membrane membranes; Peptide lipid interaction; Peptídeos antimicrobianos; Membranas miméticas; Interação peptídeo lípido

Introduction: Antimicrobial peptides have been a promising alternative to antibiotics for treating microbial infections, and have been of particular importance in recent years, since some bacteria have been shown to be resistant to some antibiotics. Objective: In this project the potential of ocelatinaPT7, a peptide isolated from the skin secretion of a Brazilian frog Leptodactylus pustulatus, was studied in permeating unilamellar vesicles. Methods: Large unilamellar vesicles were made from 1palmitoyl2oleoylphosphatidylcholine, 1palmitoyl2oleoylphosphatidylglycerol and cholesterol in the ratio of 1:0:0, 0:1:0, 1:1:0, 3:3:4 and 6:0:4, mol: mol: mol. The interaction of ocelatinaPT7 with the membranes was investigated by Carboxyfluorescein kinetics, Isothermal titration calorimetry, Optical microscopy for the study of giant unilamellar vesicles, Dynamic light scattering, Zeta potential and Differential Scanning Calorimetry. Results: The interaction of ocelatinePT7 was greater in vesicles composed of 1palmitoyl2oleoylphosphatidylglycerol than in the vesicles of 1palmitoyl2oleoylphosphatidylcholine, whereas in electrically neutral membranes containing Cholesterol it was almost null. The enthalpies of binding, given by the peptide:lipid interaction, were predominantly exothermic regardless of the lipid composition, and were even higher for membranes containing negative charges. OcelatinePT7 showed defined secondary structure only for negatively charged membranes. Finally, in the presence of the peptide, loss of contrast under optical microscopy was only observed for the neutral membranes, since for vesicles containing 1palmitoyl2oleoylphosphatidylglycerol the vesicles ruptured as if they were in the presence of a detergent. Conclusion: The results together indicate that the permeability of the peptide, the structural conformation acquired, the enthalpy of binding and its mechanism of action are dependent on the lipid composition of the membrane and that ocelatinaPT7 has potential as an antimicrobial peptide, since it has selectivity for mimetic membranes of bacteria.