Postnatal Maturation of Rat Small Intestinal Brush Border Membranes Correlates with Increase in Food Protein Binding Capacity

To investigate maturational changes of membranefood protein binding capacity, we studied bindingcharacteristics of brush border membranes isolated fromsmall intestines of newborn and adult rats. Binding of biotinylated gliadin peptides, cow's milkproteins (α-casein, β-lactoglobulin,α-lactalbumin, bovine serum albumin) and lectinswas assessed by a sensitive chemiluminescence blotassay. We found specific food protein binding with regardto saturation and inhibition. Maximal binding of mostfood proteins and several lectins to brush bordermembranes of newborn and adult rats was comparable, whereas binding of β-lactoglobulin wassubstantially less. Common or adjoining binding sitesfor the different food proteins tested were indicated bycorresponding membrane protein binding patterns and by inhibition properties of unrelated proteins.Compared to newborns, adult membrane vesicles as well asisolated membrane proteins showed higher bindingcapacities. Thus postnatal maturation of smallintestinal brush border membranes correlated withincreased food protein binding capacity.