Salivary histatin as an inhibitor of a protease produced by the oral bacterium Bacteroides gingivalis.

We examined the effect of histatin 5 from human parotid saliva on various proteases. Histatin 5 strongly inhibited a trypsin-like protease produced by Bacteroides gingivalis with an IC50 value of 55 nM. Clostripain was also inhibited (IC50 = 800 nM). Activities of other proteases were not affected significantly. Because B. gingivalis is a suspected periodontal pathogen and its proteolytic enzymes have been considered to be associated with periodontal tissue destruction, it is suggested that salivary histatins play a role as a preventive against periodontal disease.