Análise conformacional por cálculos teóricos da distinctina, peptídeo antimicrobiano isolado de anuros da espécie Phyllomedusa distincta

Abstract

Recebido em 7/2/08, aceito em 8/4/08, publicado na web em 29/4/08 CONFORMATIONAL ANALYSIS BY THEORETICAL CALCULATIONS OF DISTINCTIN, AN ANTIMICROBIAL PEPTIDE ISOLATED FROM Phyllomedusa distincta. Various studies demonstrate that different frog species produce distinct classes of biologically active peptides. These peptides can act as alternative agents against pathogenic bacteria and fungi by membrane permeability. Although studies have recently demonstrated that this process is utterly related to the secondary structure adopted by the peptide (in this case, the α-helical structure) when in contact with the bacterial membrane, the detailed mechanism is still unknown. In this work we describe a conformational analysis of distinctin, a heterodimeric peptide isolated from the skin of Phyllomedusa distincta, an anuran found in the Brazilian Atlantic Forest. The study yielded a stable geometry with a high content of the α-helical structure both in chains 1 and 2 of distinctin, showing strong interaction between them.

Theoretical Investigation of the Structural Properties of Two Crotamines Isolated from the Venom of Crotalus durissus

“…Conformational analyses of 1 and 2 were accomplished for PM3 calculations by stepwise additions of amino acid residues and geometry optimizations based on the geometries of fragments I and II, optimized by B3LYP/6-31G*(PCM; water) [27,28]. In this manner, S22 was added to the C-terminal of both fragments following geometry optimizations of these new six-residue fragments.…”