Biological Effects and Survival of Trypsin Inhibitors and the Agglutinin from Soybean in the Small Intestine of the Rat

Abstract

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, and 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.

Response of intestinal proteinase activities to the feeding of isolated winged bean (Psophocarpus tetragonolobus) and soya bean (Glycine max) trypsin inhibitors in rats

“…8 Intestinal trypsins in the middle and lower segments were more severely suppressed when winged bean TI was fed, suggesting higher survival of the trypsin±TI complex in the intestine. Although this study determined only functional activities but not resistance to intestinal proteolysis, Iwami et al 20 and Hajos et al 24 reported that the trypsin±soya bean TI complex retained its immunological reactivity even when it reached the lower parts of the intestine. Dietary TIs are regarded as having mainly two antinutritional effects: one is an increase in endogenous protein loss due to stimulated pancreatic enzyme secretion, and the other is low availability of sulphurcontaining amino acids that are included in TIs in relatively high proportions.…”

Bowman-Birk Inhibitors from Legumes: Utilisation in Disease Prevention and Therapy

“…In vivo studies have demonstrated the presence of active BBI in the small intestine. Hajós et al [39] reported the survival (~ 5 % of total ingested) of soybean BBI in an immunological reactive form in the small intestine of rats; unfortunately, the inhibitory activities of BBI were not evaluated in these experiments. More recently, it has been demonstrated that BBI from chickpea seeds can resist both acidic conditions and the action of digestive enzymes, and transit through the stomach and small intestine of pigs, generally held as a suitable model for human digestive physiology [40].…”

Purification of natural Mal d 1 and Mal d 2 allergens and monitoring of their expression levels during ripening in Golden Delicious apple

“…The antibody was developed according to Harboe & Inglid (1973) as published before (Hajós et al, 1995). Briefly, two out-bred Hungarian Vadas rabbits weighing 2-2.5 kg were used for the immunisation with highly purified Mal d 1 or Mal d 2 antigens.…”