The influence of histatin-5 fragments on the mineralization of hydroxyapatite

The adsorption of histatin 5 on hydroxyapatite (HAP) was determined and compared to that of several fragments of histatin 5, such as residues 1-16 (N16), 7-16 (M10), 9-24 (C16), 11-24 (C14), 13-24 (C12), 15-24 (C10). The influence of the adsorbed peptides on the seeded crystal growth of HAP was investigated with the constant composition method. The adsorption affinity of the peptides as well as their ability to inhibit mineralization was influenced by the length of the peptide chain. Histatin 5 showed the highest affinity, as determined by a Langmuir model, whereas the smaller C10 and C12 displayed the lowest equilibrium uptake. The smaller C10 and C12 peptides were, on the other hand, more effective as crystal growth inhibitors, indicating a more efficient coverage of surface active sites. Electrophoretic mobility data indicated an increase in the positive charge at the HAP surface in the presence of these peptides, which were efficient HAP crystallite dispersants.