Postnatal maturation of rat small intestinal brush border membranes correlates with increase in food protein binding capacity.

To investigate maturational changes of membrane food protein binding capacity, we studied binding characteristics of brush border membranes isolated from small intestines of newborn and adult rats. Binding of biotinylated gliadin peptides, cow's milk proteins (alpha-casein, beta-lactoglobulin, alpha-lactalbumin, bovine serum albumin) and lectins was assessed by a sensitive chemiluminescence blot assay. We found specific food protein binding with regard to saturation and inhibition. Maximal binding of most food proteins and several lectins to brush border membranes of newborn and adult rats was comparable, whereas binding of beta-lactoglobulin was substantially less. Common or adjoining binding sites for the different food proteins tested were indicated by corresponding membrane protein binding patterns and by inhibition properties of unrelated proteins. Compared to newborns, adult membrane vesicles as well as isolated membrane proteins showed higher binding capacities. Thus postnatal maturation of small intestinal brush border membranes correlated with increased food protein binding capacity.