Determination of functional activity of alpha 1-protease inhibitor and alpha 2-macroglobulin in human plasma using elastase.

The competitive binding of human alpha 1-antitrypsin and human alpha 2-macroglobulin to porcine pancreatic elastase was studied. Mixtures of these two protease inhibitors, when titrated against elastase give inhibition curves analogous to those obtained with human plasma. This is however not the case when the individual inhibitors are used. A theoretical treatment enabled us to devise an assay method to determine the amounts of functional activity of alpha 1-protease inhibitor and alpha 2-macroglobulin respectively in human plasma.