Gustin concentration changes relative to salivary zinc and taste in humans.

Biochemical characteristics of gustin, the major zinc protein in human parotid saliva, are similar whether the protein is isolated from subjects with normal taste acuity or from patients with hypogeusia (who may have a little as 1/5th as much parotid saliva gustin as normal subjects do). Zinc concentration in fraction II of parotid saliva, the fraction in which gustin is found on Sephadex G-150 or Sephacryl S-200 column chromatography, is proportional to the gustin content of saliva and is decreased in patients with lower than normal total parotid saliva zinc. The quantity and spectrophotometric indices of all other protein fractions isolated from patients by these column chromatographic techniques did not differ from those of normals. One patient with proven hypogeusia and low concentrations of zinc in total parotid saliva and fraction II, after 9 days of treatment with exogenous zinc, showed a 150% increase in fraction II zinc and a concomitant increase in apparent gustin levels; these changes preceded the return of normal taste function. These data demonstrate that zinc treatment can affect both taste and gustin concentrations in hypogeusia.