title: Purification and characterization of a protein inhibitor of calcium-dependent proteases from rat liver.
abstract: Soluble extracts of rat liver contain a protein inhibitor of calcium-dependent proteases. The inhibitor has an apparent Mr = 250,000 and is separated from the calcium-dependent proteases by gel-filtration chromatography in the presence of EGTA. The inhibitor has been purified by affinity chromatography using a calcium-dependent protease covalently linked to Affi-Gel 15. The inhibitor specifically binds to this affinity resin in a calcium-dependent manner and elutes in the presence of EDTA or EGTA. The purified inhibitor appears as a single protein with Mr = 125,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Presumably it is a dimer under nondenaturing conditions. The inhibitor inhibits each of two calcium-dependent proteases from rat liver and from other tissues and species. However, it has no effect on any other protease tested.
mesh_terms: D000818:Animals; D002154:Calpain; D002846:Chromatography, Affinity; D003593:Cytoplasm / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D006023:Glycoproteins / Q000302:isolation & purification* / Q000378:metabolism; D008099:Liver / Q000201:enzymology*; D008970:Molecular Weight; D011480:Protease Inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D011485:Protein Binding; D051381:Rats
chemical_list: D006023:Glycoproteins; D011480:Protease Inhibitors; C039304:calpain inhibitors; D002154:Calpain