title: Physical parameters of hydroxyapatite adsorption and effect on candidacidal activity of histatins.
abstract: Histatins 1, 3 and 5 are the major members of a histidine-rich protein family present in human salivary secretions. These proteins are distinct from many salivary proteins in their high positive charge density at neutral pH, and their antibacterial and antifungal properties. In this study, the hydroxyapatite adsorption characteristics of histatin 1, containing a single phosphoserine residue, recombinantly expressed histatin 1, native histatin 3, synthetic histatin 5 and an internal 12-residue sequence of histatin 5 were investigated. A Langmuir-type model was used to analyse the adsorption. A comparison of the affinities and binding sites of phosphorylated and recombinant histatin 1 provided an estimate of the positive influence of the single phosphoseryl group on mineral adsorption. Furthermore, an apparent correlation was shown to exist between peptide chain length and the number of binding sites. The influence of histatin 5 adsorption on its anticandidal activity was also investigated by performing Candida albicans killing assays with histatin 5 and histatin 5/hydroxyapatite suspensions. A decrease in killing activity was observed with the increase of hydroxyapatite present. The results suggest that the anticandidal properties of histatin 5 could be impaired by the conformations resulting from mineral adsorption, or that putative cellular receptors necessary for candidacidal activity are inaccessible when histatin 5 is adsorbed on hydroxyapatite.
authors.affiliation: Department of Periodontology and Oral Biology, Boston University Goldman School of Dental Medicine, Suite W201, 700 Albany Street, Boston, MA 02118-2392, USA.
authors.forename: A
authors.initials: A
authors.lastname: Yin
authors.forename: H C
authors.initials: HC
authors.lastname: Margolis
authors.forename: J
authors.initials: J
authors.lastname: Grogan
authors.forename: Y
authors.initials: Y
authors.lastname: Yao
authors.forename: R F
authors.initials: RF
authors.lastname: Troxler
authors.forename: F G
authors.initials: FG
authors.lastname: Oppenheim
mesh_terms: D000327:Adsorption; D000595:Amino Acid Sequence; D001665:Binding Sites; D002176:Candida albicans / Q000187:drug effects*; D017886:Durapatite / Q000737:chemistry*; D054808:Histatins; D006801:Humans; D008969:Molecular Sequence Data; D010748:Phosphopeptides / Q000737:chemistry / Q000235:genetics; D011506:Proteins / Q000737:chemistry / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism; D012471:Salivary Proteins and Peptides / Q000737:chemistry* / Q000235:genetics
chemical_list: C068075:HTN3 protein, human; D054808:Histatins; D010748:Phosphopeptides; D011506:Proteins; D011994:Recombinant Proteins; D012471:Salivary Proteins and Peptides; C068074:HTN1 protein, human; D017886:Durapatite