NovelN-linked oligo-mannose type oligosaccharides containing an α-d-galactofuranosyl linkage found in α-d-galactosidase fromAspergillus niger

Structures of oligosaccharides fromAspergillus niger -d-galactosidase [EC 3.2.1.22] were studied. Purified -d-galactosidase was treated withN-glycosidase F, and six kinds of oligosaccharides were isolated by gel chromatography and anion-exchange chromatography. The structures of the oligosaccharides were determined by¹H-NMR and compositional analysis to be Man₅GlcNAc₂, Man₆GlcNAc₂, Man₉GlcNAc₂, GlcMan₉GlcNAc₂, GalMan₄GlcNAc₂ and GalMan₅GlcNAc₂. From mild acid hydrolysis, methylation analysis and ROESY spectral analysis, it was ascertained that the galactosyl residue in two oligosaccharides was in the furanose form and was bound to mannose at the nonreducing end with an 1–2 linkage (GalfMan₄GlcNAc₂ and GalfMan₅GlcNAc₂).