Possible Release of an ArgGlyArgProGln Pentapeptide with Innate Immunity Properties from Acidic Proline-Rich Proteins by Proteolytic Activity in Commensal Streptococcus and Actinomyces Species

Abstract
This study suggests degradation of salivary acidic proline-rich proteins (PRPs) into potential innate-immunity-like peptides by oralStreptococcus and Actinomyces species. PRP degradation paralleled cleavage of Pro-containing substrates. PRP degradation by S. gordonii strain SK12 instantly released a Pyr1-Pro104Pro105 and a Gly111-Pro149Gln150 peptide together with a presumed Arg106Gly107Arg108Pro109Gln110pentapeptide. The synthetic Arg106Gly107Arg108Pro109Gln110peptide desorbed bound bacteria and counteracted sucrose-induced decrease of dental plaque pH in vitro.