Adsorption of human salivary proteins on synthetic hydroxyapatite

Protein adsorption of mixed saliva obtained after Millipore filtration on synthetic hydroxyapatite was studied as a function of variable concentrations of proteins for a constant weight of hydroxyapatite and for a constant protein concentration as a function of variable quantities of hydroxyapatite. Similar experiments were conducted on calcium-precipitable salivary glycoprotein. The salivary proteins and the calcium-precipitable salivary glycoprotein showed respectively an adsorption of 25 and 100 per cent. Selective adsorption of the salivary proteins remaining in the supernatant after hydroxyapatite adsorption was studied with acrylamide gel electrophoresis. The quantitative study of the gels by densitometry showed extinction only of the band corresponding to the calcium-precipitable salivary glycoprotein, indicating that this glycoprotein is selectively adsorbed. It is suggested that this salivary glycoprotein is concerned in the exogenous pellicle formation.