title: 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 Cu(2+) and Ni(2+) and, to a lesser extent, with Zn(2+). Both peptides show the potential for multiple binding sites for Cu(2+) and Ni(2+) and only a single strong binding site for Zn(2+). The binding of a third Cu(2+) ion to H3 seems to enable the binding of a fourth ion to H3. The binding of a second and third Ni(2+) 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 Cu(2+) to both H3 and H5.
authors.affiliation: Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, Department of Chemistry, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Brewer
authors.forename: G
authors.initials: G
authors.lastname: Lajoie
mesh_terms: D000595:Amino Acid Sequence; D002413:Cations, Divalent / Q000737:chemistry; D002942:Circular Dichroism; D006023:Glycoproteins / Q000737:chemistry*; D054808:Histatins; D006639:Histidine / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry; D008670:Metals / Q000737:chemistry*; D008969:Molecular Sequence Data; D011485:Protein Binding; D011489:Protein Denaturation; D011506:Proteins / Q000737:chemistry*; D012471:Salivary Proteins and Peptides / Q000737:chemistry*
chemical_list: D002413:Cations, Divalent; D006023:Glycoproteins; C068075:HTN3 protein, human; D054808:Histatins; D008670:Metals; D011506:Proteins; D012471:Salivary Proteins and Peptides; D006639:Histidine