Human saliva peroxidase: microanalytical isoelectric fractionation and properties in normal persons and in cases with neuronal ceroid-lipofuscinosis.

Human saliva contains a high peroxidase activity that can be estimated spectrophotometrically with the hydrogen donor p-phenylenediamine and the substrate hydrogen peroxide from 20 mul of material. The pH optimum of the enzyme with citrate-phosphate buffer is 5.5. After microanalytical isoelectric fractionation 3 main isoenzyme components at pI 8.6, 6.5 and 4.3, and a number of isoenzyme subfractions at pI 9.5, 7.3 and 3.8 are detectable. In 3 patients with the juvenile form of neuronal ceroid-lipofuscinosis (type Spielmeyer-Vogt), in which a deficiency of leukocyte peroxidase had been reported by other authors, both the total activity of saliva peroxidase and the activity of individual isoenzymes were found to be within normal limits. These findings are not consistent with a generalized peroxidase deficiency in this disease.