The several facets of Trichogin GA IV: High affinity Tb(III) binding properties. A spectroscopic and molecular dynamics simulation study

Trichogin GA IV (TrGA) is an antimicrobial peptide isolated from Trichoderma longibrachiatum. The amino acid sequence of TrGA is rather peculiar, because it is characterized by three Aib and four Gly residues, which confer unique dynamic and structural properties. In a previous study, we found that TrGA shows excellent binding properties to Ca(II) and lanthanide Gd(III) ions in acetonitrile solutions. Within the lanthanide ions, Tb(III) ions possess fascinating optical characteristics, such as luminescence which greatly improves after coordination. Here, we present the results of our spectroscopic and molecular dynamics investigations on the Tb(III) ion-binding properties of an N-alpha-Fmoc functionalized analog of Trichogin GA IV (F0TrOMe). The high Tb(III) ion-F0TrOMe affinity, together with the proteolytic resistance and membrane affinity of the natural compound, confers to this system potentially promising applications in several fields, such as bioimaging and bioanalytical assays.