title: Kinetics of association of human proteinases with human alpha 2-macroglobulin.
abstract: Association rates have been determined for the interaction of human alpha 2-macroglobulin with human neutrophil elastase, cathepsin G, and human plasma kallikrein. Both of the neutrophil enzymes are rapidly inactivated by this inhibitor; however, the inactivation of plasma kallikrein is much slower. Comparison of the rates of inactivation with those already established for other inhibitors clearly indicate that alpha 1-proteinase inhibitor is the controlling inhibitor for neutrophil elastase and alpha 1-antichymotrypsin for cathepsin G, alpha 2-macroglobulin acting only as a secondary inhibitor. The control of plasma kallikrein would appear to be rather poor since neither alpha 2-macroglobulin nor C1-inhibitor appears to react very rapidly with this proteinase. Thus, a primary role for alpha 2-macroglobulin in directly inactivating proteinases in blood, under normal physiological conditions, remains to be established.
mesh_terms: D001665:Binding Sites; D056649:Cathepsin G; D002403:Cathepsins / Q000097:blood*; D006801:Humans; D007610:Kallikreins / Q000097:blood*; D007700:Kinetics; D046911:Macromolecular Substances; D009504:Neutrophils / Q000201:enzymology*; D010196:Pancreatic Elastase / Q000097:blood*; D011485:Protein Binding; D012697:Serine Endopeptidases; D000511:alpha-Macroglobulins / Q000378:metabolism*
chemical_list: D046911:Macromolecular Substances; D000511:alpha-Macroglobulins; D002403:Cathepsins; D007610:Kallikreins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G; D010196:Pancreatic Elastase