Banca de DEFESA: SUEDSON DE CARVALHO SILVA RODRIGUES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : SUEDSON DE CARVALHO SILVA RODRIGUES
DATA : 22/07/2019
HORA: 14:00
LOCAL: a definir
TÍTULO:

STRUCTURAL AND BIOLOGICAL STUDIES OF PEPTIDE DERIVED FROM STIGMURIN, STIGA15 AND INTERACTION WITH BIOMIMETIC MEMBRANES

PALAVRAS-CHAVES:

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

PÁGINAS: 90
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Orgânica
ESPECIALIDADE: Estrutura, Conformação e Estereoquímica
RESUMO:

Due to the broad spectrum of biological activities reported in the literature for peptides present in the venom of scorpions, an increase has been observed in the studies of these molecules, especially the antimicrobial peptides, which are investigated as strategic alternatives to face problems such as resistance to conventional antibiotics. It is known that the mechanism of action of antimicrobial peptides occurs in large part by the interaction with the microorganism membrane, causing destabilization of the lipid bilayer, resulting in the formation of pores, which leads to cell lysis. However, the details of these interactions are not yet fully known and can vary significantly from peptide to peptide, therefore, membrane-peptide interaction studies with biomimetic media are necessary. The present work proposes the synthesis and the characterization of the bioactive peptide StigA15, designed from the primary sequence of Stigmurin, which has originally been isolated from the Tityus stigmurus scorpion. The peptide was obtained from Fmoc solid phase peptide synthesis and Isothermal Titration Calorimetry (ITC) and Circular Dichroism (CD) and Nuclear Magnetic Resonance (NMR) spectroscopies were used as main research tools and the respective experiments were performed in media that mimic membrane environments. When compared the activity of StigA15 to that of the of the wild-type Stigmurin, it was observed that the substitution of two serine residues by two charged lysines resulted in higher activities against Gram-positive and negative bacteria as well as against fungi. According to preliminary studies, it has been identified that StigA15 has a higher hydrophobic moment and therefore could be inserted more deeply in the membrane than Stigmurin. StigA15 presents selectivity towards pattogen cells, since it presents very low hemolysis rates at the active antimicrobial concentrations. This selectivity is further supported by ITC experiments that indicated significatly stronger interactions of StigA15 with anionic vesicles, when compared to zwitterionic vesicles. CD and NMR spectroscopies indicated that the peptide adopts helical conformations in membrane mimetic enviorenments. In addition, NMR spectrosccopy proved that the peptide shows high amphipathicity which is, together with its net positive charge (+4), a feature commonly found in several antimicrobial peptide sequences. Therefore, here is presented a novel peptide sequece with high biotechnological potential

MEMBROS DA BANCA:
Presidente - 1569526 - RENATA MENDONÇA ARAUJO
Interno - 1803692 - FABRICIO GAVA MENEZES
Externo à Instituição - EDILBERTO ROCHA SILVEIRA - UFC