The soybean trypsin inhibitor was first crystallized by Kunitz in 1945 and is one of several such inhibitors found in soybeans. Its molecular weight is 21,500 ± 800 daltons and the optimum pH is 7.0. Soybean inhibitor inhibits trypsin mole-for-mole and to a lesser extent chymotrypsin. Enzyme activity definition： The activity of the inhibitors is expressed as the amount of twice crystallized trypsin (Aladdin Item: T128774) inhibited per milligram of inhibitor. 1mg trypsin ≥180 TAME units, 10,350 BAEE units, 3,450 USP/NF units.
