The Glc2Man2-fragment of the N-glycan precursor – a novel ligand for the glycan-binding protein malectin?

The Glcalpha(1-->3)Glcalpha(1-->3)Manalpha(1-->2)Man tetrasaccharide (Glc(2)Man(2)-fragment), a substructure of the natural N-glycan precursor, was synthesized. The interaction of this fragment with the protein malectin, a carbohydrate binding protein localized in the endoplasmatic reticulum, was investigated by (1)H(15)N HSQC experiments and isothermal calorimetry. The chemical shift perturbations of nuclei in the protein's backbone caused by the binding of the Glc(2)Man(2)-fragment to malectin suggest a binding mode like the known ligand nigerose.