A CONSTANT COMPOSITION KINETICS STUDY OF THE INFLUENCE OF SALIVARY CYSTATINS, STATHERIN, AMYLASE AND HUMAN SERUM-ALBUMIN ON HYDROXYAPATITE DISSOLUTION

The influence of salivary cystatins, statherin, amylase and human seru m albumin on the dissolution kinetics of hydroxyapatite has been inves tigated using the constant composition method. At a pH of 6.0, salivar y cystatins and statherin all decreased the dissolution rate by about 30% at a surface concentration of 5.0 x 10(-8) mol m-2. Although littl e difference between neutral cystatin SN and acidic cystatin S was see n at pH 6.0, when the reaction was performed at a similar degree of un dersaturation at neutral pH (6.95), cystatin S was the more efficient inhibitor. At a surface concentration of 5.0 x 10(-8) mol m-2, cystati n SN and cystatin S decreased the rates of dissolution by 35% and 30% at pH 6.0 and by 40% and 65% at a pH of 6.95 respectively. Human serum albumin and amylase were more efficient dissolution inhibitors than e ither of these salivary cystatins at pH 6.0 and 4.8. Moreover, in all cases the influence of the adsorbed proteins increased with extent of reaction.