Transglutaminase-mediated glycosylation of whey protein isolate with glucosamine: effects on structure, functional properties, and intestinal barrier function

This study investigates the effects of transglutaminase (TGase)-mediated glycosylation on the structure, functional properties, and intestinal barrier function of whey protein isolate (WPI). Structural analysis revealed that the covalent interaction between glucosamine and WPI led to a more stable and ordered protein structure. Compared with WPI, the glycosylated WPI exhibited improved foaming, emulsifying, and antioxidant properties. TGase-mediated glycosylation also reduced the degree of hydrolysis of WPI under in vitro digestion conditions. Furthermore, a cellular intestinal barrier model was established using Caco-2 cells, and treatment with digested glycosylated WPI significantly increased transepithelial electrical resistance while decreasing paracellular permeability. RT-PCR and Western blot analyses demonstrated that the digest of glycosylated WPI up-regulated the expression of tight junction proteins (Occludin, Claudin-1, and ZO-1), thereby enhancing intestinal barrier function. This study provides new insights into the development of food proteins that combine desirable functional properties with biological activities.