Banca de QUALIFICAÇÃO: SUEDSON DE CARVALHO SILVA RODRIGUES

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : SUEDSON DE CARVALHO SILVA RODRIGUES
DATA : 13/06/2019
HORA: 09:00
LOCAL: a definir
TÍTULO:

Synthesis and structural and interaction studies with membranes of peptides derived from Stigmurin

PALAVRAS-CHAVES:

Antimicrobial peptide, peptide-membrane interaction, structure-activity relationship.

PÁGINAS: 85
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Orgânica
ESPECIALIDADE: Estrutura, Conformação e Estereoquímica
RESUMO:

Due to the broad spectrum of antimicrobial activity of bioactive peptides, an increase has been observed in the study of these molecules as strategic alternatives to face problems such as the resistance of conventional antibiotics. It is known that the mechanism of action of antimicrobial peptides largely occurs through interaction with the membrane of the microorganism, causing destabilization of the lipid bilayer, resulting in the formation of pores, which can lead to cell lysis. However, the details of this interaction are not yet fully known, therefore, membrane-peptide interaction studies with biomimetic media are necessary. The present work proposed the synthesis and characterization of a potential bioactive peptide designed from the primary sequence of stigmurin, called StigA15. Calorimetry of Isothermal Titration (ITC), Circular Dichroism (CD) and Nuclear Magnetic Resonance (NMR) for the analogue were used as main research tools. All of these experiments were developed in media that mimic membrane environments, such as micelles and phospholipid vesicles. For the StigA15 peptide, it was observed that the substitution by two charged lysines resulted in increased activity against Gram-positive and negative bacteria and fungi, with StigA15 being more active for these strains than the native peptide. According to preliminary studies, it has been identified that StigA15 has a higher hydrophobic moment and therefore could be inserted more at the surface of the membrane and interact more effectively than stigmurin. It is possible to observe a selectivity for the peptide StigA15, due to its low hemolysis rate in the active antimicrobial concentrations. This was confirmed by ITC studies that demonstrated the increased interaction of StigA15 in anionic vesicles than in zwitterionic vesicles. It has been found by CD and NMR that the peptide is α-helix-structured when in contact with membrane mimetic media. In addition, a high amphipathicity of the derivative was confirmed by NMR. Therefore, an unpublished peptide with biotechnological potential is presented. 

MEMBROS DA BANCA:
Interno - 1959889 - DAVI SERRADELLA VIEIRA
Interna - 2140775 - LIVIA NUNES CAVALCANTI
Externo ao Programa - 1544647 - MATHEUS DE FREITAS FERNANDES PEDROSA
Presidente - 1569526 - RENATA MENDONÇA ARAUJO