Peptidomimetics of Naturally Occurring Pellicle Peptides: Effects on Hydroxyapatite Crystal Growth

Objectives: To test the hypothesis that duplication/hybridization of functional domains of in vivo naturally occurring pellicle peptides amplifies the inhibitory effect for hydroxyapatite crystal growth, function related to enamel remineralization and dental calculus formation. This study assessed the ability of naturally occuring statherin pellicle peptide, called DR9, in inhibiting hydroxyapatite crystal growth. Additionally, a specific amino acid sequence from histatin 3 (RR14) was introduced to the hybrid peptides for further testing.
Methods: Peptidomimetic peptides (DR9-DR9, DR9-RR14, DR9-VPAGL-RR14 and DR9-VPLSL-RR14), in addition to, DR9, statherin, or distilled water (control) were tested in eight different concentrations to evaluated the effect on hydroxyapatite crystal growth inhbition. A microplate colorimetric assay was used to quantify hydroxyapatite crystal growth (Xiao et al., 2015). Experiments were made in triplicate and IC 50 was established for each group. ANOVA and a Student–Newman–Keuls test for pairwise comparisons were carried out to compare the values among the groups.
Results: DR9-DR9 amplified the inhibitory effect for hydroxyapatite crystal growth when compared to single DR9 or statherin (p<0.05), proving that functional domain multiplication is a strong protein evolution pathway. Interestingly, the hybrid peptide DR9-RR14 demonstrated an intermediate inhibitory effect when compared with the other groups such as DR9, DR9DR9 and statherin.
Conclusions: This study used peptidomimetic approach to investigated a potential evolution protein pathway related to duplication and/or hybridization of acquired enamel pellicle’s natural peptide constituents. Knowledge obtained here may provide a basis for the development synthetic peptides for therapeutic use against dental caries and periodontal disease