Síntese, caracterização e estudos estruturais de análogos do peptídeo antimicrobiano Cn-AMP1 em meios biomiméticos

• Autor(a) principal: Matos, Carolina Oliveira
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• dARK ID: ark:/38995/001300000dbpx
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/5298
• topic: NMR; Peptide; Antimicrobial; NMR; Peptide; Antimicrobial; CIENCIAS EXATAS E DA TERRA::QUIMICA

Antimicrobial peptides are part of the innate defense of several organisms, and represent candidate drugs in their natural form, allowing for the development of modified peptides with improved pharmacological profiles. In this context, this study aimed of the synthesis of Cn-AMP1, an antimicrobial peptide naturally isolated from green coconut water, which has activity against fungi, gram-positive and gram-negative bacterias well as effects on the proliferation of cancer cells and low toxicity to mammalian cells, the analogs [Trp9] Cn-AMP1 and [Gly9] Cn-AMP1 were also obtained by solid phase peptide synthesis using the Fmoc strategy. The characterization and purification of the peptides were performed by mass spectrometry and high-performance liquid chromatography. Structural studies of the peptides were performed by circular dichroism (CD) and nuclear magnetic resonance (NMR) in the presence of biomimetic enviroments. CD and NMR results indicated that the peptides do not present preferential conformations in aqueous solutions, however adopt helical conformations in membrane mimetic environments. CD studies have shown that Cn-AMP1 and [Gly9] Cn-AMP1 do not adopt show defined conformation in the presence of DPC micelles at different pH values, however the peptide [Trp9] Cn- AMP1 showed a small a-helical content in the presence of 100mM DPC. In the presence of SDS the spectra of all peptides showed helical profiles at both pH 4, pH 7 as well as in the absence of buffer. NMR experiments indicated the interaction of the peptides [Trp9] Cn-AMP1 and [Gly9] Cn-AMP1 with SDS micelles at pH 4 (25 °C), and structural calculations indicated that [Trp9]Cn- AMP1 adopts an α-helical conformation between Val2-Gly8, and that [Gly9] Cn- AMP1 adopts an α -helical conformation between Val2-Arg5. Dynamic light scattering and zeta potential experiments were performed to investigate the effect of addition of peptides into phospholipid vesicles. All of the peptides caused variations on the POPC:POPG (3:1) and POPC, LUVs hydrodynamic radios, however major changes were observed for the anionic vesicles due to the strong interaction between the arginine residue of the peptides and the negativelly charge of membrane.