title: β-Galactosidase from Ginkgo biloba seeds active against β-galactose-containing N-glycans: purification and characterization.
abstract: In this study, we purified an acidic β-galactosidase to homogeneity from Ginkgo biloba seeds (β-Gal'ase Gb-1) with approximately 270-fold purification. A molecular mass of the purified β-Gal'ase Gb-1 was estimated about 35 kDa by gel filtration and 32 kDa by SDS-PAGE under non-reducing condition, respectively. On the other hand, β-Gal'ase Gb-1 produced a single band with a molecular mass of 16 kDa by SDS-PAGE under reducing condition. The N-terminal amino acid sequences of 32 kDa and 16 kDa molecules were the same and identified as H-K-A-N-X-V-T-V-A-F-V-M-T-Q-H-, suggesting that β-Gal'ase Gb-1 may function as a homodimeric structure in vivo. When complex-type N-glycans containing β-galactosyl residues were used as substrates, β-Gal'ase Gb-1 showed substantial activity for β1-4 galactosyl residue and modest activity for β1-3 galactosyl residue with an optimum pH near 5.0. Based on these results, the involvement of β-Gal'ase Gb-1 in the degradation of plant complex-type N-glycans is discussed.
authors.affiliation: a Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science , Okayama University , Okayama , Japan.
authors.forename: Md Ziaur
authors.initials: MZ
authors.lastname: Rahman
authors.forename: Megumi
authors.initials: M
authors.lastname: Maeda
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Kimura
mesh_terms: D000595:Amino Acid Sequence; D005690:Galactose / Q000737:chemistry; D020441:Ginkgo biloba / Q000201:enzymology*; D007700:Kinetics; D011134:Polysaccharides / Q000737:chemistry; D012639:Seeds / Q000201:enzymology*; D013379:Substrate Specificity; D001616:beta-Galactosidase / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D011134:Polysaccharides; D001616:beta-Galactosidase; D005690:Galactose
keywords: Ginkgo biloba; N-glycan degradation; glycosidase; plant N-glycan; β-galactosidase