Human parotid saliva protein composition: dependence on physiological factors.

The relative concentrations of the major proteins in human parotid saliva as measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis varied greatly between the six individuals included in this study but were remarkably constant for a given individual. Individual relative parotid protein concentrations differed in salivas collected under unstimulated and stimulated conditions but were at least partially independent from circadian and feeding effects. In addition, the relative concentrations of certain salivary proteins decreased with continued lemon-drop stimulation. A total of 29 different bands was composited from the six subjects. Five of the bands had mobilities corresponding with those of calibration proteins selected for their known occurrence in parotid saliva. Only those proteins comprising at least 0.75% of the total protein concentration were detected. Relative protein concentrations of parotid saliva samples collected 12 mo apart from given individuals were identical.