Enzymatic properties of a Ginkgo biloba endo-beta-N-acetylglucosaminidase and N-glycan structures of storage glycoproteins in the seeds.
An endo-beta-N-acetylglucosaminidase has been purified to homogeneity from mature seeds of Ginkgo biloba. The molecular mass of the endo-beta-N-acetylglucosaminidase, named Endo-GB, was estimated to be around 63 kDa by SDS-PAGE and around 62 kDa by Hiprep S-200 chromatography, respectively. The substrate specificity has been explored with regard to the pyridylaminated N-glycans. Several high mannose-type sugar chains bearing alpha-1,2-mannosyl residue(s), Man9-6GlcNAc2-PA, were the most favored substrates followed by Man5GlcNAc2-PA and a typical hybrid-type structure (GlcNAc1Man5Glc NAc2-PA) which does not bear an alpha-1,2-mannosyl residue. On the contrary, endo-GB could hardly hydrolyze the common core pentasaccharide of N-glycan (Man3GlcNAc2-PA) and the xylose-containing sugar chains (Man4-3Xyl1Glc NAc2-PA, Man3Fuc1Xyl1GlcNAc2-PA) being widely distributed in plant glycoproteins. Furthermore, we analyzed the structures of N-glycans conjugated to storage glycoproteins in the mature Ginkgo seeds to see the occurrence of endogenous substrates for Endo-GB. The structural analysis showed, however, only xylose-containing type N-glycans (Man3Fuc1Xyl1GlcNAc2 (95%) and Man3Xyl1 GlcNAc2 (5%)), which can not be substrate for Endo-GB, predominantly occur in the storage glycoproteins.
Kimura
Y
Y
Department of Bioresources Chemistry, Faculty of Agriculture, Okayama University, Japan.
Matsuo
S
S
Takagi
S
S
D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000032:analysis; D002848:Chromatography, DEAE-Cellulose; D002849:Chromatography, Gas; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D032462:Cycadopsida / Q000737:chemistry* / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D006023:Glycoproteins / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010940:Plant Proteins / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry* / Q000378:metabolism; D012639:Seeds / Q000737:chemistry* / Q000201:enzymology; D013050:Spectrometry, Fluorescence; D013379:Substrate Specificity
D002241:Carbohydrates; D006023:Glycoproteins; D010940:Plant Proteins; D011134:Polysaccharides; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase