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Updated: Aug 14, 2026

The Cell-based L-Glutathione Protection Assays to Study Endocytosis and Recycling of Plasma Membrane Proteins
Published on: December 13, 2013
High affinity binding site-mediated prevention of chemical absorption across the gastrointestinal tract
M V Rasmussen1, T T Barker, L K Silbart
1Department of Animal Science, University of Connecticut, Center for Environmental Health, CANR, Box U-39, 3636 Horsebarn Road Extension, Storrs, CT 06269, USA.
Abstract:
Preventing mucosal absorption of low-molecular weight compounds such as carcinogens, toxins and drugs could help prevent many diseases. To characterize the effects of dose and timing on high-affinity binding site mediated sequestration of specific chemical ligands in the gastrointestinal tract, avidin was perorally-administered to mice either prior to or mixed with 3H-biotin. Avidin enhanced fecal 3H-biotin excretion in a dose-dependent manner, consistent with the accepted mechanism of egg white-induced biotin deficiency syndrome. Avidin administration up to 4 h before 3H-biotin administration also enhanced fecal 3H-biotin excretion. Activated charcoal (AC) reduced 3H-biotin absorption when mixed with 3H-biotin before ingestion, but was ineffective when ingested prior to 3H-biotin. These studies suggest that ingestion of high-affinity protein binding sites can establish an absorptive barrier at the gastrointestinal mucosa to prevent the uptake of unwanted low molecular-weight chemicals.
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