title: In vitro binding and in vivo clearance of human alpha 2-macroglobulin after reaction with endoproteases from four different classes.
abstract: The binding of human alpha 2-macroglobulin complexed with trypsin, papain, thermolysin and cathepsin-D to murine macrophages was studied at 4 degrees C. Similar dissociation constants (0.4 nM) were determined for all of the complexes except alpha 2-macroglobulin-cathepsin-D (0.7 nM). Radioiodinated alpha 2-macroglobulin-protease complexes were injected into mice, and the clearance studied. Native alpha 2-macroglobulin cleared slowly, as previously reported, while greater than 50% of the complexes formed with trypsin, papain and thermolysin cleared in less than 5 min. The clearance of alpha 2-macroglobulin-cathepsin-D was biphasic, suggesting that only about half the alpha 2-macroglobulin was present in a reacted complex.
mesh_terms: D000818:Animals; D002402:Cathepsin D; D002403:Cathepsins / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008264:Macrophages / Q000378:metabolism*; D008657:Metabolic Clearance Rate; D051379:Mice; D008810:Mice, Inbred C57BL; D010206:Papain / Q000378:metabolism; D013820:Thermolysin / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism*; D000511:alpha-Macroglobulins / Q000378:metabolism*
chemical_list: C028939:alpha-2-macroglobulin-trypsin complex; D000511:alpha-Macroglobulins; D002403:Cathepsins; D010450:Endopeptidases; D014357:Trypsin; D010206:Papain; D002402:Cathepsin D; D013820:Thermolysin