Summary
A crude preparation of a proteolytic enzyme inhibitor from potatoes was purified by
means of column chromatography with SE-Sephadex C-50 using a stepwise gradient of
concentration and pH when eluting proteins from the column. The inhibitor preparation
thus obtained is stable for a 28 day period of storage and resistant to the action
of various physical and chemical factors harmful to the spatial structure of proteins.
The potato protease inhibitor markedly inhibits the activity of trypsin, chymotrypsin,
plasmin and alkaline proteases from Aspergillus flavus. The inhibition of pronase
and a mixture of acid cellular proteases by this inhibitor is considerably less. Pepsin,
cathepsin D, and collagenase are not affected by this inhibitor. The potato inhibitor has a marked
inhibitory effect on plasmin fibrinolytic activity both in purified systems and in
the plasma euglobulin fraction. It also protects the fibrinogen from the action of
this enzyme. It does not, however, inhibit plasminogen activation under the influence
of either streptokinase or urokinase.
