Effect of deglycosylation of salivary glycoproteins on oral malodour production

Abstract

Putrefaction of saliva is commonly used as an in-vitro assay in oral malodour investigations. Aim: To exam the hypothesis that deglycosylation of salivary glycoproteins promotes oral malodour production. Design: Porphyromonas gingivalis-mediated putrefaction of salivary glycoproteins was tested following preincubation of saliva in the presence of β-galactosidase with or without glycosidic inhibitor (galactosamine), and in the presence of glucose with or without a non-glycosylated protein (bovine serum albumin). Methods: Malodour was determined by two odour judges, and volatile sulphides by using a sulphide monitor. Salivary glycoprotein degradation was measured densitometrically following electrophoresis on SDS-PAGE. Results: The addition of β-galactosidase promoted salivary glycoprotein degradation and concomitant malodour production, whereas addition of a glycosidic inhibitor (D-galactosamine) inhibited this process. Glucose inhibited salivary glycoproteins putrefaction, but this inhibitory effect was mitigated when a non-glycosylated protein (BSA) was added. Conclusions: Deglycosylation of salivary glycoproteins may be an initial step in oral malodour production. This process exposes the protein core of the glycoprotein, which is then further degraded by Gram-negative microorganisms under anaerobic conditions.