Trypsin and α-chymotrypsin inhibitors from potatoes: Isolation and some properties

At least 13 inhibitors of trypsin and α-chymotrypsin were shown to be present in the juice of potato tubers by polyacrylamide gel electrophoresis. 9 of these proteins were isolated by isoelectric focussing. Isoelectric points, specific activities and amino acid compositions were determined. One of the inhibitors could be shown to exist as a tetramer, which in the presence of α-chymotrypsin dissociates in two steps to form I 2E and IE complexes.