Carbohydrate-binding properties of goat secretory glycoprotein (SPG-40) and its functional implications: structures of the native glycoprotein and its four complexes with chitin-like oligosaccharides

The crystal structures of four complexes of a signalling glycoprotein from goat (SPG-40) with oligosaccharides of different lengths have been determined. The structures of the complexes with GlcNAc₃, GlcNAc₄, GlcNAc₅ and GlcNAc₆ revealed the positions of these oligosaccharides in the carbohydrate-binding groove and provided insights into the binding mechanism of oligosaccharides to SPG-40.