Purification and characterization of a Co(II)-sensitive α-mannosidase from Ginkgo biloba seeds

Kwan Kit Woo, Mitsuhiro Miyazaki, Shintaro Hara, Mariko Kimura, Yoshinobu Kimura

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)


An α-mannosidase was purified from developing Ginkgo biloba seeds to apparently homogeneity. The molecular weight of the purified α-mannosidase was estimated to be 120 kDa by SDS-PAGE in the presence of 2-mercaptoethanol, and 340 kDa by gel filtration, indicating that Ginkgo α-mannosidase may function in oligomeric structures in the plant cell. The N-terminal amino acid sequence of the purified enzyme was Ala-Phe-Met-Lys-Tyr-X-Thr-Thr-Gly-Gly-Pro- Val-Ala-Gly-Lys-Ile-Asn-Val-His-Leu-. The α-mannosidase activity for Man5GlcNAc1 was enhanced by the addition of Co 2+, but the addition of Zn2+, Ca2+, or EDTA did not show any significant effect. In the presence of cobalt ions, the hydrolysis rate for pyridylaminated Man6 GlcNAc1 was significantly faster than that for pyridylaminated Man6GlcNAc2, suggesting the possibility that this enzyme is involved in the degradation of free N-glycans occurring in developing plant cells (Kimura, Y., and Matsuo, S., J. Biochem., 127, 1013-1019 (2000)). To our knowledge, this is the first report showing that plant cells contain an α-mannosidase, which is activated by Co2+ and prefers the oligomannose type free N-glycans bearing only one GlcNAc residue as substrate.

Original languageEnglish
Pages (from-to)2547-2556
Number of pages10
JournalBioscience, Biotechnology and Biochemistry
Issue number12
Publication statusPublished - Dec 2004


  • Co (II)
  • Free N-glycan metabolism
  • Ginkgo biloba
  • Plant glycoprotein
  • α-mannosidase

ASJC Scopus subject areas

  • Biotechnology
  • Analytical Chemistry
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Molecular Biology
  • Organic Chemistry


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