PROTEASE INHIBITORS IN TRACHEOBRONCHIAL SECRETIONS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 101  (5) , 747-757
Abstract
The isolation and characterization of 3 protease inhibitors from tracheobronchial secretions are described. As starting material, pooled secretions from patients with tracheostomies was used. The isolation procedure consisted of precipitation with 3% perchloric acid (the major acid-stable inhibitors remain in solution) affinity chromatography on trypsin-Sepharose and preparative zone electrophoresis. Three distinct inhibitors were found. One was a basic protein with evidence of size and charge heterogeneity but immunologic homogeneity, MW = 15,850 .+-. 1200 daltons, 12,600 .+-. 700, 6500 .+-. 500. Two inhibitors were acidic proteins, MW = 63,400 .+-. 3200 (Al) and 19,960 .+-. 1500 (All) daltons. The basic inhibitor has tyrosine as the solve aminoterminal amino acid. For the 2 acidic inhibitors, an aminoterminus was not found. All 3 inhibitors contained neutral sugars and amino sugars but no sialic acid. They inhibit trypsin, chymotrypsin and human granulocytic elastase. The 2 acidic inhibitors are immunologically related; they are apparently derived from serum ITI. Inhibitor All originates from inhibitor Al, probably by limited proteolysis by several proteases. The concentration of the basic inhibitor in bronchial secretions of 42 patients with obstructure lung disease was 0.206 .+-. 0.15 mg/ml.