Estudo estrutural por 1h-rmn de peptídeos bioativos isolados da secreção cutânea de Hypsiboas Albopunctatus E Leptodactylus Labyrinthicus
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Data
2012-02-24
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Universidade Federal de Goiás
Resumo
Currently, the emergence of fungi, bacteria and viruses resistant to
multiple drugs has stimulated interest in the development of antimicrobial
peptides with increased therapeutic potential. They generally have properties
of extreme importance as antimicrobial selective toxicity, rapid action,
specific mechanisms of action and a broad spectrum of antimicrobial action.
Many of these features can be found in peptides isolated from frog skin
secretions.
The main factor that differentiates antimicrobial peptides from other
commonly antibiotics used in the conventional therapy is related to their
mechanism of action. The driving force for much of the action of antimicrobial
peptides is their ability to lysis cell membranes, rapidly killing a broad
spectrum of microorganisms. Accordingly, the conformation of the peptide
has a great importance in their interaction with the amphiphilic structure of
biological membranes. The determination of the tridimensional structure by
Nuclear Magnetic Resonance (NMR) technique allows the identification of
the spatial position of each amino acid residue and highlighting those that are
important for its action and, therefore, could be modified to increase the
antimicrobial activity. The study of the three-dimensional structure of peptides
in solution is an advantage of the NMR spectroscopy, since it can simulate
the physiological environment, by means of surfactants.
In this context, the tridimensional structures of two synthetic peptides:
ocellatin-P1G16 (GLLDTLKGAAKNVVGGLASKVMEKL-NH2), isolated from
the amphibians Leptodactylus labyrinthicus, and hylin a1 (IFGAILPLALGALKNLIK-NH2), isolated from Hypsiboas Albopunctatus, were
proposed by NMR.
The amphipathic caracter can be visualized by separation of the helix
into two distinct sides, one hydrophobic (nonpolar) and the other hydrophilic
(polar). The peptide hylin a1 in presence of SDS-d25 showed helical structure
between residues Ile-5 to Ile-17 and the peptide ocellatin-P1G16 in SDS-d25
micelles showed a α-helical structure between residues Leu-3 to Lys-24, both
are presented in amphipathic α-helix
Finally, the molecular analyses of amphipathicity, electrostatic
interaction, polarity and exchange hydrogen/deuterium, corroborate the
proposed model, suggesting a model of parallel orientation to the peptide
hylin a1 and the peptide ocellatin-P1G16 a parallel orientation, but with the cterminal
portion immersed in the micelle SDS-d25 between residues Ser-19 to
Leu-25, as observed by analyzing exchange hydrogen/deuterium. These
structural characteristics make these peptides promising candidates for the
development of a new antimicrobial drug.
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Citação
ALVES, Eliane Santana Fernandes. Structural study by 1h-nmr of bioactive peptides isolated skin of secretion Hypsiboas albopunctatus And Leptodactylus labyrinthicus. 2012. 112 f. Dissertação (Mestrado em Educação em Química) - Universidade Federal de Goiás, Goiânia, 2012.