The fate of the bowman-birk trypsin inhibitor from soybeans in the digestive tract of chicks

1. 1. Intestinal absorption of the Bowman-Birk trypsin inhibitor from soybeans was studied comparatively in chicks by direct follow-up of absorbed radioactive inhibitor and by radioimmunological estimation of the unlabelled inhibitor. 2. 2. Initial studies, performed in vitro by the inverted sac technique, suggested that both the native inhibitor and its degradation products were absorbed. 3. 3. However, the results obtained for in situ and in vivo experiments indicated that the absorption of the native inhibitor is negligible. 4. 4. Most of the inhibitor is degraded during its passage through the intestine, and the majority of the degradation products is excreted in the feces. 5. 5. The effects of ingested inhibitor on pancreas enlargement and on secretion of pancreatic enzymes stems from an indirect effect on the intestine.