Structural, membrane interaction and biological studies of PS-O1 and LyeTx I-b peptide derivatives

• Autor(a) principal: Lucas Raposo Carvalho
• Data de Publicação: 2022
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Repositório Institucional da UFMG
• Texto Completo: http://hdl.handle.net/1843/51378; https://orcid.org/0000-0002-6476-4531
• topic: Antimicrobial peptides; Phylloseptins; LyeTx I-b; Nuclear magnetic resonance - NMR spectroscopy; Peptide-membrane interactions; Glucotriazole-peptides; PEGylated peptides; Arginine; Química orgânica; Peptídios – Síntese; Produtos de ação antimicrobiana; Ressonância magnética nuclear; Arginina; Formação de anéis (Química); Cromatografia liquida de alta eficiência; Testes biológicos; Atividade antifúngica; Citotoxidade de mediação celular; Agentes antibacterianos

Antimicrobial peptides (AMPs) are promising drug candidates when fighting bacterial resistance, being molecules with many mechanisms of action. Furthermore, the skin secretion of anurans and spider poisons are rich sources of AMPs, and phylloseptine PS-O1, alongside LyeTx I-b, are peptides of interest to our research group. Peptide alteration strategies, such as post-translational modifications and residue insertion, aim to improve the biological properties of these drug candidates. As such, in this work, six compounds were synthesized, being two peptides (PS-O1 and R1G2-PS-O1) and two propargylic derivatives ([Pra1 ]PS-O1 and R[Pra]PS-O1) by Fmoc-SPPS and two glucotriazole peptides (PS-O1 GtP and R1A2-PS-O1 GtP) using the CuAAC reaction. Two peptides, LyeTx I-bcys and LyeTx I-bPEG, were synthesized by collaborator Júlio César Moreira Brito. PS-O1 derivatives were synthesized (8.7 to 26.5% yield), purified by RP-HPLC (73.4 to 91.5% yield), with purities ranging from 92% to 98%, and analyzed by MALDI-TOF-MS. Circular dichroism was used to analyze their conformational prefer ences in the presence of TFE/H2O mixtures, SDS and DPC micelles, and POPC and POPC/POPG 3:1 vesicles, indicating α-helical structural motifs starting from specific concentrations for all media except POPC LUVs. The three-dimensional structure of PS-O1, PS-O1 GtP, R1G2-PS-O1, R1A2-PS-O1 GtP, LyeTx I-bcys, and LyeTx I-bPEG was determined by 2D NMR experiments, revealing various α-helical percentages and positions. While the introduction of a glucose unit increased structure formation for PS-O1, an opposite effect was observed for R1G2-PS-O1, being potentially attributed to different helix stabilizing interactions at the N -terminus. A high degree of structural similarity between LyeTx I-bcys and LyeTx I-bPEG was observed. Finally, antifungal biological studies for PS-O1 derivatives show that R1G2-PS-O1 is considerably more active than the other three, supporting structural data obtained by NMR analyses.