Further studies on proteinase inhibitors separated from human serum by deae sephadex chromatography

Proteinase inhibitors adsorbed from human serum on DEAE Sephadex A 25 0.25 or 0.3 mol/l NaCl were purified by affinity chromatography on a trypsin-Sepharose 4B column, by gel filtration, and by DEAE cellulose chromatography. Small amounts of TCI-I (desorbed from the ion-exchange between 0.25-0.3 mol/l NaCl), and TCI-II (desorbed at NaCl concentration above 0.3 mole/l) with high specific activity were obtained. The low recovery of inhibitory activity (below 9% was due to a molecular transformation of these inhibitors after contact with the immobilized trypsin. The low-molecular weight derivatives were formed that lost their ability to adsorbe on ion-exchanger at 0.25 or 0.3 mole/l salt concentration.