Purification and substrate specificity of a ginkgo biloba glycosidase active in β-1,2-xylosidic linkage in plant complex type n-glycans

Abstract

The β-xylosidase, which is active against plant complex type N-glycans, was purified to homogeneity from Ginkgo biloba seeds. The N-terminal amino acid sequence, G-S-A-A-G-N-R-, of the Ginkgo β-xylosidase (β-Xyl'ase Gb) was consistent with the deduced internal amino acid sequence of an Arabidopsis β-xylosidase (AtBXL1). β-Xyl'ase Gb hydrolyzed the β1-2 xylosyl residue from Xylβ1-2Manβ1-4GlcNAcβ1-4GlcNAc-PA and Xylβ1-2Manβ1-4GlcNAcβ1-4(Fucβ1-3)GlcNAc-PA, but not that from Manβ1-6(Manβ1-3)(Xylβ1-2)Manβ1- 4GlcNAcβ1- 4(Fucβ1-3)GlcNAc-PA.