In vivo digestion of a thaumatin-like kiwifruit protein in rats
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Food allergens must exhibit sufficient gastrointestinal stability to reach the intestinal mucosa where absorption and sensitization can occur. Therefore, investigation of protein stability within the gastrointestinal tract may provide a prospective test for the allergenic potential of novel proteins. The aim of this work was to examine the effect of the fruit matrix and purified pectin on the digestion in vivo of kiwifruit allergens in the rat gastrointestinal system. The major kiwi allergen, Act d 2, was quantified in several compartments of the gastrointestinal tract by a monoclonal antibody-based ELISA. Protein intactness was demonstrated by immunoblot. Under conditions of complex food digestion in vivo, a pepsin-labile protein survived passage from the stomach to the caecum during a 3-h period. Decay of Act d 2 in the rat gut exhibited an exponential pattern. Ingestion of kiwifruit was followed by a decrease in both total and specific pepsin activity. When purified, Act d 2 allerge...n was consumed together with pure apple pectin; both gastric acidity as well as specific and total pepsin activity declined and thus protected 23% of the ingested allergen from digestion for 90 min. In conclusion, ingestion of pectin-rich fruits and particularly pectin supplements may have a protective action on pepsin-labile allergens and prolong their survival in both gastric and duodenal juices, enabling efficient uptake and presentation to the immune system. © Springer Science+Business Media, LLC 2010.