Adult female rats were sacrificed 4 hr after p.o. administration of the Captamine given in molar equivalents to 30 mg/100 g of cysteamine-HCI.

The normal human fetal skin fibroblast cell line were used for activity evaluation. For the analog inhibition and Km experiments, an 18-mkl aliquot of an inhibitor or substrate solution in 40 mM Mops/Tris, pH 7.0, buffer containing 0.25 M sucrose and 60 mM DTT was mixed with 9 mkl of 142 mkM [3H]cysteamine in 20 mM Mops/Tris, pH 7.0, buffer containing 0.25 M sucrose and 1 mM DTT; incubation mixtures were warmed to 37 °C, then 9mkl aliquots of ice-cold lysosomal suspension in 40 mM Mops/Tris, pH 7.0, buffer containing 0.25 M sucrose were added at time 0 and incubated for the indicated period of time at 37 °C; a 30-mkl aliquot was removed from each incubation mixture, added to 12 ml of ice-cold PBS, and filtered through a GF/A filter (Whatman, 24 mm); the filter was washed twice with 12-ml portions of ice-cold PBS and mixed with 16 ml of Cytoscint scintillation fluid (ICN). Filters were allowed to equilibrate in scintillation fluid for 18-24 h prior to counting for radioactivity. Lysosome independent radioactivity retained on the filters, determined by substituting 40 mM Mops/Tris, pH 7.0, buffer in 0.25 M sucrose for the lysosomes, was subtracted from radioactivity retained on filters of lysosome-containing samples.