Structural requirements for the binding of oligosaccharides and glycopeptides to immobilized wheat germ agglutinin.
The structural requirements for the interaction of asparagine-linked oligosaccharide moieties of glycoproteins with wheat germ agglutinin (WGA) were investigated by using affinity chromatography on a WGA-Sepharose column. So-called hybrid-type glycopeptides obtained from ovalbumin [Yamashita, K., Tachibana, Y., & Kobata, A. (1978) J. Biol. Chem. 253, 3862--3869] were found to have high affinity for WGA--Sepharose, whereas high mannose-type and complex-type glycopeptides were shown to have low affinity. The elution profiles of various glycopeptides modified by glycosidase treatment, Smith periodate degradation, acetolysis, and hydrazinolysis showed that the GlcNAcbeta 1--4Manbeta 1--4GlcNAc beta 1--4GlcNAc-Asn structure was essential for the binding of glycopeptides to a WGA-Sepharose column. Thus, it was revealed that both the N,N'-diacetylchitobiose moiety and the beta-N-acetylglucosaminyl residue linked to C-4 of the beta-linked mannose residue contributed to the interaction of the glycopeptide with WGA-Sepharose. The substitution at C-6 of the innermost beta-N-acetylglucosaminyl residue by an alpha-fucosyl residue or at C-6 of the beta-linked mannose residue by another mannose residue in the above structure reduced the affinity of glycopeptides for the column.