Background: A procedure for the isolation of highly purified lysosomes from normal rat kidney is described.
Methods: The method depends on the swelling of mitochondria when the postnuclear supernatant fraction is incubated with 2 mM Ca2+. The lysosomes can then be separated from the swollen mitochondria by Percoll density gradient centrifugation.
Results: The lysosomal fraction obtained by our method was enriched more than 30-fold in terms of marker enzymes with a yield of about 11%. Electron microscopic examination and the measurement of the activities of marker enzymes for various subcellular organelles indicated that our lysosomal preparation was essentially free from contamination by other organelles.
Conclusion: We believe that this procedure for isolating kidney lysosome will be useful in the study of the mechanisms of specific modification, processing and catabolism of proteins.