Combined Full-length and Truncated Salivary Peptides' Effect on Demineralisation

Objectives: The organic acquired enamel pellicle film is formed on the tooth surface by selective adsorption of salivary components. Salivary peptides such as statherin and histatin-1 are effective inhibitors of crystal growth following adsorption onto enamel preventing crystal growth sites. Previous studies have concentrated on the influence of peptides individually. However, in the oral environment the pellicle is made up of a number of different peptides.

The aim was to measure the effect of full-length and truncated statherin (STN) and histatin-1 (HTN), individually, and in combination, on the demineralisation rate of hydroxyapatite (HA) enamel analogues, using Scanning Microradiography (SMR).
Methods: Synthetic full length peptides (STN43 and HTN38), and truncated N-terminal 21-mer peptides (STN21 and HTN21) were synthesised (Peptide Protein Research, UK). Demineralisation solution (0.1M acetic acid, pH 4.0) was circulated over HA discs located within SMR cells for 72h. The discs were then washed with 50ml of distilled water for 15min. The discs were then treated for 24hr with 2.0ml of the test peptides dissolved in PBS with a total peptide concentration of 0.2mM in each case. Demineralisation solution circulation continued for a further 72h. Mineral loss was measured throughout using SMR.
Results: Results are shown in Table 1.
Conclusions: This study shows that HA demineralisation rates were reduced similarly following the exposure to full length and truncated peptides individually, but to a greater extent in combination, suggesting a synergy of action. Further, the combination of truncated N-terminal 21-mers of both peptides displayed greater reduction in HA demineralisation rates suggesting that the C-terminal amino acids of the full length peptides are less involved in demineralisation inhibition than the N-terminal.