Turnover of lysosomal proteins and induction and distribution of rat liver proteinases, after treatment with Triton WR-1339.

from case 2, however, showed a shoulder at pH4.5 due probably to some residual glucosaminidase A and glucosaminidase B activity. The optimum for both glucosaminidase and galactosaminidase activities ofleucocytes from this patient was pH4.5; here a greater proportion of hexosaminidase A and hexosaminidase B remains, masking the C form. The total hexosaminidase activity of these leucocytes was 4 % of control values, whereas activities of the fibroblasts were 1.4 and 2.8 % for cases 1 and 2 respectively. The lack of hexosaminidase C activity towards galactosaminide is shown in Fig. l(b) where the hexosaminidase C peak at pH5.5-6.0 is now decreased to equal or below that of the residual pH4.5 forms. Isoelectric focusing of control fibroblast glucosaminidase showed (Fig. 2c) the characteristic two peaks of A and B forms, the PI values of each being pH5.5 and 8.2 respectively, whether assayed at pH4.5 or 5.5. However, focusing of Sandhoff fibroblasts (Figs. 2a and 26) produced a different major peak, at pH4.65 (assayed at pH4.5) or pH4.8 (assayed at pH 5 . 9 , corresponding to hexosaminidase C activity. This difference in the apparent PI of hexosaminidase C is difficult to reconcile, especially since the results were obtained from common columns. Nevertheless, since the latter PI value (pH4.8) was obtained when assaying at the pH optimum for hexosaminidase C, this value would seem more likely to be correct. The presence again in case 2 Sandhoff fibroblasts of some hexosaminidase A isevident from theshoulder ofactivity at pH5.4(Fig. 2 4 whenassayed at pH4.5 (the pH optimum of this enzyme). Some hexosaminidase B was present as a broad band of decreased activity in both Sandhoff fibroblasts. Further isoelectric focusing studies, in a narrower pH gradient will, it is hoped, provide a better understanding of hexosaminidase C in Sandhoff tissues.