Evaluation of the metal binding properties of the histidine-rich antimicrobial peptides histatin 3 and 5 by electrospray ionization mass spectrometry

Abstract

Electrospray ionization mass spectrometry (ESI‐MS) was used to investigate metal ion interactions with salivary peptides histatin 3 (H3) and histatin 5 (H5). Conformational changes of these peptides in the presence of metal ions were studied using circular dichroism spectroscopy. H3 and H5 formed high affinity complexes with Cu2+ and Ni2+ and, to a lesser extent, with Zn2+. Both peptides show the potential for multiple binding sites for Cu2+ and Ni2+ and only a single strong binding site for Zn2+. The binding of a third Cu2+ ion to H3 seems to enable the binding of a fourth ion to H3. The binding of a second and third Ni2+ ion to H5 has a similar effect in enabling the binding of a fourth ion. None of the metal ions examined stabilized a regular secondary structure for either peptide. Subtle changes in overall conformation are seen with the addition of Cu2+ to both H3 and H5. Copyright © 2000 John Wiley & Sons, Ltd.

Zinc and copper bind to unique sites of histatin 5

“…The catalytic properties of zinc^histatin complexes a¡ecting fusion of small unilamellar vesicles in vitro suggests a mechanism for histatin activity based on metal association [10]. The NMR evidence presented in this study indicates speci¢city with respect to the histidyl and acidic amino acid side-chains participating in metal binding interactions, and extends previous ¢ndings demonstrating unique stoichiometries and binding a¤nities for zinc^and copper^histatin 5 complexes [8,9].…”

How Does It Kill?: Understanding the Candidacidal Mechanism of Salivary Histatin 5

“…1) for Cu and Ni (ACTUN motif, encompassing the first 3 N-terminal amino acids, Asp-SerHis) as well as for Zn (HEXXH motif at the C terminus [72,73]). Multiple strong binding sites within the binding motif are believed to occur for Cu, while Zn has only one strong putative metal binding site (74).…”

Synthesis of peptides with hydroxamic acid side chain appendages.

“…The gentleness of electrospray ionization allowed detection of very weakly associated complexes under the proper experimental conditions (Brewer, 2000). Once several parameters including pH, ionic strength, temperature and source voltage parameters were carefully controlled, the ionization and volatilization process of ESI-MS did not lead to complex decomposition.…”