ABSTRACT
Human saliva was fractionated to determine the components required for production and accumulation of the antimicrobial oxidizing agent, hypothiocyanite ion (OSCN-). The required components were: 1) peroxidase activity and thiocyanate ion (SCN-), 2) the saliva sediment, which produced hydrogen peroxide (H2O2) in the presence of oxygen and a divalent cation, and 3) heat-stable factors of the saliva supernatant. The supernatant factors were separated into high- and low-mol wt fractions. The high-mol wt fraction contained both peptide and carbohydrate, and its activity was partially inhibited by proteolytic treatment. The low-mol wt fraction contained carbohydrate and could be replaced by a number of mono- and di-saccharides. Glucosamine and N-acetyl glucosamine were the most effective, whereas neutral sugars such as sucrose were less effective. Sucrose competed with glucosamine, so that lower levels of OSCN- were obtained with increasing amounts of sucrose. The sugars stimulated production of H2O2 by the saliva sediment. Production of H2O2 was greater in the presence of glucosamine than of neutral sugars. Also, the ratio of OSCN- accumulation to H2O2 production was greater in the presence of glucosamine. The results suggest that peroxidase-mediated antimicrobial activity is modulated by the carbohydrate composition of whole saliva and by certain protein and glycoprotein components.
Subject(s)
Peroxidases/metabolism , Saliva/enzymology , Thiocyanates/metabolism , Anti-Infective Agents , Carbohydrate Metabolism , Glucosamine/metabolism , Humans , Hydrogen Peroxide/metabolism , Saliva/metabolismABSTRACT
The median concentration of hypothiocyanite (OSCN-) in freshly collected whole saliva was 10 microM. The OSCN- concentration increased to a median value of 36 microM during incubation for one h at 37 degrees in vitro. This increase was partially inhibited by adding certain sugars (especially sucrose). The results suggest that OSCN- is a naturally occurring component of human saliva. Also, dietary carbohydrate may inhibit OSCN- accumulation and antimicrobial action in saliva.
