title: Metabolism of leupeptin and its effect on autophagy in the perfused rat liver.
abstract: Metabolism of the potent, thiol proteinase inhibitor, leupeptin, was studied in the perfused rat liver. This bacterial peptide (2.5 mg) caused the lysosomes to become enlarged and filled with electron-dense material. The subcellular distribution of the lysosomal enzyme, beta-D-hexosaminidase, was altered, the major change being a 50% loss of its activity from the L-fraction of the homogenate. The enzyme became redistributed in the other homogenate fractions. The density of the leupeptin-formed lysosomes compared to normal organelles was increased from 1.206 to 1.230 g/ml. Radioactive [3H]leupeptin was slowly taken up by a perfused liver (approximately 0.06 mumole/h/g liver) and almost immediately appeared in the bile in a form still capable of inhibiting papain. Liver radioactivity was concentrated in both the lysosomal (39%) and soluble fractions (38%) of the tissue homogenate.
mesh_terms: D000818:Animals; D002499:Centrifugation, Density Gradient; D006596:Hexosaminidases / Q000378:metabolism; D007976:Leupeptins / Q000378:metabolism / Q000494:pharmacology*; D008099:Liver / Q000378:metabolism / Q000648:ultrastructure*; D008247:Lysosomes / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D008854:Microscopy, Electron; D009842:Oligopeptides / Q000494:pharmacology*; D051381:Rats; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D007976:Leupeptins; D009842:Oligopeptides; D006596:Hexosaminidases