Inhibition by Lactoferrin and κ-Casein Glycomacropeptide of Binding of Cholera Toxin to its Receptor

Abstract

Inhibition from binding of Cholera toxin (CT) to Chinese hamster ovary (CHO) -k1 cells and ganglioside G_M1 by lactoferrin (Lf) and κ-casein glycomacropeptide (GMP) from cow's milk was examined. Both Lf and GMP effectively reduced the CT-derived morphological changes in CHO-K1 cells. The competitive binding assay demonstrated that both Lf and GMP inhibited the binding of CT to G_M1, although their affinity for CT was lower than that of G_M1. The inhibitory effect of Lf and GMP seemed to be attributed to their terminal sialic acid, although the sugar chain sequence only partially fitted to the CT-receptor.