Modification of human parotid saliva proteins by oral streptococcus sanguis

Polyacrylamide gel electrophoresis was used to analyze the effect of Streptococcus sanguis on the anionic proteins in human parotid gland saliva. Cell-free culture supernatants and washed-cell preparations from 23 strains of S. sanguis caused marked modification of various salivary proteins. Control studies showed that the alterations in protein profiles by the bacteria were not due to attachment of protein to the cells. Protease inhibitors were used to confirm that proteolysis by distinct enzymatic activities was responsible for most of the modifications. There was no discernible relationship between the degradation patterns and the various immunologic or genetic groups of S. sanguis. Proteins which contained high concentrations of proline were extensively degraded by S. sanguis. This effect could be blocked with the protease inhibitor phenylmethyl-sulphonyl fluoride.