Effect of mercurial compounds on structure-linked latency of lysosomal hydrolases.
1. A partially purified lysosomal preparation was obtained from adult mouse livers by sucrose-density-gradient centrifugation of a large-granule fraction. 2. This lysosome-enriched subfraction was contaminated approx. 10% by mitochondrial cytochrome c oxidase and malate dehydrogenase. 3. Free acid phosphohydrolase and beta-glucuronidase contributed less than 10% of the total (Triton X-100-solubilized) activity in contrast with approx. 30% free N-acetyl-beta-d-glucosaminidase when assayed in an iso-osmotic incubation system. 4. Exposure of the lysosomal preparation to inorganic Hg(2+) ions and organic mercurials (p-chloromercuribenzoate, phenylmercuric acetate) induced an irreversible loss of structure-linked latency with resulting enzyme activation. 5. Maximal activation was related to log [Hg(2+)] and pH. The response was all-or-none for individual particles; the dose-response curve portrayed the variation in particle resistance within the lysosomal population. 6. l-Cysteine and GSH totally prevented Hg(2+) ion-induced hydrolase activation. Ascorbate provided approx. 50% protection. 7. The three lysosomal hydrolases were differentially activated at constant [Hg(2+)], suggesting a different pattern of binding, unique for each enzyme studied.
D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology; D001665:Binding Sites; D002499:Centrifugation, Density Gradient; D003545:Cysteine / Q000494:pharmacology; D003576:Electron Transport Complex IV / Q000378:metabolism; D005978:Glutathione / Q000494:pharmacology; D006026:Glycoside Hydrolases / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006867:Hydrolases / Q000378:metabolism*; D008099:Liver / Q000166:cytology / Q000201:enzymology*; D008247:Lysosomes / Q000187:drug effects / Q000201:enzymology*; D008291:Malate Dehydrogenase / Q000378:metabolism; D008297:Male; D008628:Mercury / Q000494:pharmacology*; D051379:Mice; D010088:Oxidoreductases / Q000378:metabolism*; D013268:Stimulation, Chemical
D010088:Oxidoreductases; D008291:Malate Dehydrogenase; D003576:Electron Transport Complex IV; D006867:Hydrolases; D000135:Acid Phosphatase; D006026:Glycoside Hydrolases; D008628:Mercury; D005978:Glutathione; D003545:Cysteine; D001205:Ascorbic Acid