Evaluating the copper-binding properties of the antifungal peptide histatin 5

Histatins are a family of histidine-rich peptides that are found in saliva. This family of peptides has antifungal properties. In this family, histatin 5 is the most efficient antifungal peptide against Candida albicans. The mechanism for the antifungal activity of histatin 5 is still unknown. Previous studies suggest that the metal-binding properties of histatin 5 may have some connection to its antifungal activity. Although there is some evidence that histatin 5 can bind Cu(II), currently there is no conclusive data on the Cu(I) binding properties of histatin 5. This work focuses on investigating the copper-binding properties of histatin 5 and analyzing the role these copper-binding properties may play in the antifungal activity of histatin 5. Model peptides of histatin 5 have been synthesized and copper binding studies were performed by UV-Vis spectroscopy and mass spectrometry. Reactive oxygen species formation process was studied by fluorescence assay.