title: Biochemical evidence for an endocytically inactive population of lysosomes.
abstract: The peroxidase dependent, diaminobenzidine (DAB) density shift procedure was applied to the characterization of lysosomes from Chinese hamster ovary (CHO) cells. Peroxidase activity was localized in lysosomes by a 15-18 h internalization period. After treatment with DAB, the distribution of peroxidase activity in Percoll gradients was shifted, as a population, to a higher density. A bimodal distribution which included a low density population was observed for the native lysosomal enzyme beta-hexosaminidase after DAB treatment. A second lysosomal enzyme, alpha-fucosidase, was strongly inhibited by DAB treatment with the residual activity corresponding in distribution to the light beta-hexosaminidase population. The occurrence of a low density lysosomal population after the DAB procedure suggests the existence of an endocytically inactive lysosomal population in fibroblasts. Probable physiological candidates for such a population are discussed.
mesh_terms: D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D004705:Endocytosis / Q000187:drug effects; D005260:Female; D006596:Hexosaminidases / Q000378:metabolism*; D008247:Lysosomes / Q000201:enzymology* / Q000502:physiology; D010053:Ovary; D010544:Peroxidases / Q000378:metabolism*; D010655:Phenylenediamines / Q000494:pharmacology; D005644:alpha-L-Fucosidase / Q000378:metabolism*; D001619:beta-N-Acetylhexosaminidases
chemical_list: D010655:Phenylenediamines; C034193:1,2-diaminobenzene; D010544:Peroxidases; D006596:Hexosaminidases; D005644:alpha-L-Fucosidase; D001619:beta-N-Acetylhexosaminidases