BIOLOGICAL EFFECTS AND SURVIVAL OF TRYPSIN-INHIBITORS AND THE AGGLUTININ FROM SOYBEAN IN THE SMALL-INTESTINE OF THE RAT

The survival in the rat small intestine of soybean agglutinin or Kunitz or-Bowman-Birk trypsin inhibitors was studied by SDS- and native polyacrylamide gel electrophoresis, transblotting, trypsin inhibitor activity assays, sind immunochemical determinations. As the inhibitors were bound in enzyme complexes in the small intestine, functional assays were unsuitable. However, as free and bound inhibitors reacted similarly with their antibodies, survival could be assayed by immunoblotting and ELISA. In addition to the mucosa-bound agglutinin, 8.6% of the original dose was free in the gut lumen and this, by moving further down in the small intestine, could have extended the wasteful gut growth from proximal to distal parts. Although only 4.8% of the Bowman-Birk inhibitor survived, most (76%) of the Kunitz inhibitor remained immunochemically intact. Accordingly, stimulation of pancreatic growth and enzyme secretion by the inhibitors, particularly the Kunitz, may have contributed to the total antinutritive effect of soybean.