Structural analysis of N-linked oligosaccharides of equine chorionic gonadotropin and lutropin beta-subunits

Experimental analysis of the structure of N-linked oligosaccharides of equine lutropin (eLH) and chorionic gonadotropin (eCG) reveals that the oligosaccharides of the eCG beta subunit are of the tri-, tetra-, bi-, and monoantennary complex-type while those of eLH beta subunit are of bi- and monoantennary complex-type and of the hybrid-type. The eCG-beta oligosaccharides possess 20% and 16% of poly-N-acetyllactosamine and bisecting GlcNAc structures, respectively, while the eLH-beta oligosaccharides contain 18% of the bisected GlcNAc structures. The charge groups of the oligosaccharides of eLH-beta and eCG-beta differ despite similar protein moiety, with the terminal charge groups and stem structures of the carbohydrate moiety regulating the biological activity of the enzymes.