Three-dimensional structure of the α-MSH-derived candidacidal peptide [Ac-CKPV]2

:  Previous research has shown that the immunomodulatory peptide α-melanocyte-stimulating hormone (α-MSH) and its carboxy-terminal tripeptide KPV (Lys-Pro-Val α-MSH11−13) have antimicrobial influences. By inserting a Cys-Cys linker between two units of KPV, we designed the dimer [Ac-CKPV]2 that showed excellent candidacidal effects in pilot tests and was the subject of further investigations. [Ac-CKPV]2 was active against azole-resistant Candida spp. Therefore, the molecule appeared a promising candidate for therapy of fungal infections and was the subject of a structural study. 1H-NMR and restrained mechanic and dynamic calculations suggest that the peptide adopts an extended backbone structure with a β-turn-like structure. These results open a pathway to development of additional novel compounds that have candidacidal effects potentially useful against clinical infections.