Abnormal breakdown of alpha2-macroglobulin-trypsin complex in cystic fibrosis.

The complex of trypsin with purified alpha2-macroglobulin from normals and patients with 
cystic fibrosis was studied. The formed complex failed to reveal any 
proteolytic activity toward a high molecular weight substrate whereas the esterolytic 
activity towards a low molecular weight substrate was retained. This esterolytic 
activity was resistant to inhibition by a high molecular weight inhibitor. 
During iincubation at 38 degrees C the complex with normal alpha2-macroglobulin 
was slowly inhibited by the high molecular weight inhibitor and regained 
activity with the high molecular weight substrate. This phenomenon was not 
obtained when the alpha2- macroglobulin from cystic fibrosis was examined. These 
data suggest that the gradual conversion of normal alpha2-macroglobulin-trypsin complex into 
an alpha2-macroglobulin fragment-trypsin complex is deficient in patients with cystic fibrosis. 
