Antimicrobial Peptides Chelating Lanthanide Ions: the Case of Trichogin GA IV Analogues and Terbium(III)

摘要

Lipopeptaibols are the members of a family of antimicrobial peptides characterized by the presence of a lipid chain at the N-terminus and a high content of a-aminoisobutyric acid (Aib). Trichogin GA IV is one of the most representative compounds of this class, being characterized by peculiar conformational properties and a high affinity to the membrane phase. X-Ray diffraction studies showed that this peptide is folded in a mixed 3_(10)/α-helix conformation, while NMR, CD and IR absorption experiments indicated that this structure is also predominantly populated in solution. Recently, we have characterized the aggregation properties and partition equilibria of trichogin GA IV fluorescent analogues in aqueous solution and in the membrane phase, showing that their membrane permeabilization capability is strictly correlated to the concentration of aggregated forms in the lipid phase [1]. We have also recently found that trichogin GA IV shows peculiar binding properties to Ca(II) and several lanthanide ions [e.g. Gd(III), Tb(III)] [2].