Adsorption of Human Salivary Proteins to Hydroxyapatite: A Comparison Between Whole Saliva and Glandular Salivary Secretions

Abstract

The protein compositions of in vitro pellicles formed from whole saliva and parotid and submandibular secretions were determined by use of synthetic hydroxyapatite as a model for dental enamel. The adsorbed and unadsorbed protein fractions were analyzed by amino acid analysis and both anionic and cationic discontinuous polyacrylamide gel electrophoresis. For further characterization of the in vitro pellicle, the adsorbed fractions were subjected to gel filtration on Sephadex G-100 and reversed-phase chromatography on C18 columns. Amylase, acidic and glycosylated proline-rich proteins, statherins, and histatins were identified in the parotid-derived pellicle. Detailed analysis of the statherin-containing fractions resulted in the observation of several statherin-like proteins. The use of cationic gel electrophoresis allowed for the identification of histatin 3 and histatin 5, which have not been previously detected in pellicle formed in vitro. The protein composition of submandibular-derived pellicle was similar to that of parotid-derived pellicle except for the presence of cystatins and the absence of glycosylated proline-rich proteins. In contrast, in vitro pellicle derived from whole saliva exhibited a vastly different composition, consisting primarily of amylase, acidic proline-rich proteins, cystatins, and proteolytically-derived peptides. The results indicate that acidic phosphoproteins as well as neutral and basic histatins from pure secretions selectively adsorb to hydroxyapatite, whereas in whole saliva some of these proteins are proteolytically degraded, dramatically changing its adsorption pattern.

Adsorption behaviour and surfactant elution of cationic salivary proteins at solid/liquid interfaces, studied by in situ ellipsometry

“…On hydrophilic silica surfaces the steep slopes of the isotherms and the high adsorbed amounts of the investigated proteins (correlating to side-on and end-on monolayer at concentrations relevant in saliva) suggests that these proteins have strong driving forces for adsorption, comparable to those observed for salivary secretions [14,33,34,38] and single key-pellicle proteins [41,48].…”

“…In vitro studies have shown that the candidacidal activity of histatin 5 is impaired when adsorbed to surfaces [10,11], but upon desorption it is reactivated. Histatins have been identified in both in vitro and in vivo formed pellicles [12][13][14].…”

Global secretome analysis identifies novel mediators of bone metastasis

“…The salivary cystatins, however, have not been shown to strongly antagonize Cathepsin B [62], and instead have been hypothesized to function in salivary glands as inhibitors of harmful proteinases expressed by pathogens [63]. Additionally, the salivary cystatins have been suggested to have high affinity for hydroxyapatite, the main mineralized component of bone tissue [64]. Thus, whether salivary cystatin production functions in bone metastasis via facilitating evasion of the immune system, or homing to the bone tissue, or by a different mechanism altogether, remains to be determined.…”

Solid state NMR studies of molecular recognition at protein–mineral interfaces

“…Statherin efficiently hinders the crystallization of hydroxyapatite in the supersaturated environment of saliva [68][69][70][71][72][73]. The statherins have historically served as one of the best characterized models for understanding the functional activities of proteins in the physicalchemical control of hydroxyapatite growth.…”