Evaluating the Copper-binding Properties of the Antifungal Peptide Histatin 5

Histatin is a family of histidine-rich peptides that are found in saliva. This family has antifungal property, among which 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 suggested that the metal-binding properties of histatin 5 may have some connection to its antifungal activities. However, 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 a fluorescence assay.