Trypsin Inhibitor

Among the many factors that have been implicated as having an adverse effect on the nutritional value of proteins is a class of proteins, known as protease inhibitors, that has the ability to inhibit the proteolytic activity of proteases of diverse origin. The protease inhibitors that have been isolated from soybeans and other legumes fall biochemically into two main categories: (1) those that have a molecular weight of 20,000 to 25,000 Da with relatively few disulfi de bonds and a specifi city directed primarily toward trypsin (Kunitz inhibitor), and (2) those that have a molecular weight of only 6000 to 10,000 Da with a high proportion of cystine residues and are capable of inhibiting chymotrypsin as well as trypsin at independent binding sites (Bowman-Birk inhibitor).