A plausible role of salivary copper in antimicrobial activity of histatin-5 —Metal binding and oxidative activity of its copper complex

Histatin-5 (Hn5) is an antimicrobial salivary peptide of 24 amino acids. Two specific metal-binding sites were revealed with electronic, NMR, and EPR spectroscopy. The complex Cu 2 II –Hn5 effectively oxidizes catechol, exhibiting enzyme-like kinetics ( k cat = 0.011 and 0.060 s −1 and k cat/ K m = 19 and 50 M −1 s −1 without and with 12.8 mM H 2O 2, respectively). The significant oxidative activity may contribute to the biological activity of this antibiotic metallopeptide.