Dissolution of lysozyme-coated hydroxyapatite

The effect of the adsorption of chicken egg-white lysozyme, a basic protein, on the dissolution kinetics of synthetic hydroxyapatite (HAP) is studied at a constant pH of 5.0. It is confirmed that lysozyme adsorption occurs in spite of the positive net charge of the HAP surface and is favoured by high concentrations of phosphate ions. This implies that adsorption sites for the protein are phosphate ions adsorbed onto HAP. The dissolution kinetics performed with lysozyme-coated HAP in the presence of the protein in solution show no significant difference from kinetics obtained with uncoated HAP surfaces. This absence of effect is explained by considering the limited coverage of the HAP by the protein, whose low molecular weight, globular shape, rigidity and stability lead to a small number of anchoring points.