Ms. Lamkin et al., TEMPORAL AND COMPOSITIONAL CHARACTERISTICS OF SALIVARY PROTEIN ADSORPTION TO HYDROXYAPATITE, Journal of dental research, 75(2), 1996, pp. 803-808
Salivary proteins bind to enamel surfaces and hydroxyapatite in a high
ly selective manner. Numerous studies have identified these proteins a
s primarily proline-rich proteins, cystatins, statherin, and histatins
. Previously, the hydroxyapatite-binding potential of these proteins h
ad been characterized in systems consisting of singly purified protein
and adsorbent. The purpose of this study was to investigate the adsor
ption of each protein in the presence of complete salivary secretion.
Proteins, shown to adsorb to hydroxyapatite, were purified, biotinylat
ed, and added back to the remaining proteins to form a series of recon
stituted secretions. The adsorption of each biotinylated protein in th
e reconstituted secretion to hydroxyapatite was then measured as a fun
ction of time. Results indicated that three different adsorption patte
rns occur. A simple hyperbolic pattern is characteristic of amylase, g
lycosylated proline-rich protein (PRG), and cystatin. A faster adsorpt
ion process is observed for PRP-3, PRP-L PIF-f, and statherin. A more
complex pattern, exhibiting a rapid phase followed by a slower phase,
is characteristic of PRP-1, PRP-2, PIF-s, and histatins. These results
suggest that there are different adsorption processes involved in the
binding of salivary proteins to hydroxyapatite. Two possible mechanis
ms are direct adsorption of protein to hydroxyapatite and indirect ads
orption of protein by interacting with other proteins already bound to
hydroxyapatite.