Effect of disulfide bridges deletion on the conformation of the androctonin, polyphemusin-I, and thanatin antimicrobial peptides: molecular dynamics simulation studies

In this work, the role of the disulfide bridges in the maintenance of the secondary structure of the antimicrobial peptides androctonin, polyphemusin-I, and thanatin is analyzed on the basis of their structural characteristics and of three of their respective mutants, andry4, poly4, and thany2, in which all the cysteine residues have been replaced with tyrosine residues. The absence of the disulfide bridges in andry4, poly4, and thany2 seems to be compensated by an overall enforcement of the original hydrogen bonds and by extra attractive interactions between the aromatic rings of the tyrosine residues. In spite of the mutations, the original β-hairpin structures are maintained in the three mutants, but the best conformational similarities are found for the androctonin/andry4 pair.