Peptide Characterization of Mature Fluorotic and Control Human Enamel

Abstract

Exposure to high fluoride levels during amelogenesis causes enamel fluorosis. This study aimed to determine and compare the amino acid sequences in the enamel of fluorotic and control teeth. This investigation included enamel samples obtained from erupted and non-erupted third molars with either TF grade 4-6 (n=7) fluorosis or no sign of fluorosis (controls, n=7). The samples were kept frozen at -20 °C until protein extraction. Samples were etched and processed with a cocktail of proteinase inhibitors and immediately analyzed. Matrix Assisted Laser Desorption/Ionization-Time-Of-Flight/Time-of-Flight Mass Spectrometry (MALDI-TOF/TOF) followed by MASCOT search aided the peptides analysis. The more abundant peptides bore the N-terminal amelogenin sequences WYQSIRPPYP (which is specific for the X-encoded amelogenin) and MPLPPHPGHPGYINF (which does not show sexual dimorphism) were not different in control or fluorotic enamel. There was no missing proteolytic cleavage in the fluorotic samples, which suggested that the increased amount of protein described in fluorotic enamel did not stem from the decreased ability of proteinases to cleave the proteins in humans. This study showed how to successfully obtain peptide from superficial enamel. A relatively low number of teeth was sufficient to provide good data on the actual peptides found in mature enamel.

Genes Involved in the Enamel Development Are Associated with Calcium and Phosphorus Level in Saliva

“…Mature enamel contains enamel protein-specific peptides that can be recovered from mature contemporary teeth [Porto et al, 2006; Porto et al, 2011a], as well as from ancient teeth [Porto et al, 2011b] and fluorotic teeth [Porto et al 2016]. Dissolution of the whole enamel allowed the identification of enamel protein-specific peptides [Castiblanco et al, 2015].…”

Tooth Enamel and Its Dynamic Protein Matrix

“…A comprehensive proteomic characterization of proteins or peptides in mature fluorotic enamel appears not to be published yet. However, recent proteomic analyses of fluorosis-affected teeth from individuals with a 8 ppm fluoride content in their drinking water showed no different protein content compared to controls [ 106 ]. Only amelogenin peptides were identified in fluorosed teeth and control samples.…”