A novel vanadium reductase, Vanabin2, forms a possible cascade involved in electron transfer

Norifumi Kawakami, Tatsuya Ueki, Yusuke Amata, Kan Kanamori, Koichi Matsuo, Kunihiko Gekko, Hitoshi Michibata

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)


The unusual ascidian ability to accumulate high levels of vanadium ions at concentrations of up to 350 mM, a 107-fold increase over that found in seawater, has been attracting interdisciplinary attention for a century. Accumulated VV is finally reduced to VIII via VIV in ascidian vanadocytes. Reducing agents must therefore participate in the reduction. Previously, we identified a vanadium-binding protein, Vanabin2, in which all 18 cysteines form nine disulfide bonds. Here, we report that Vanabin2 is a novel vanadium reductase because partial cleavage of its disulfide bonds results in the reduction of VV to VIV. We propose that Vanabin2 forms a possible electron transfer cascade from the electron donor, NADPH, via glutathione reductase, glutathione, and Vanabin2 to the acceptor, and vanadium ions conjugated through thiol-disulfide exchange reactions.

Original languageEnglish
Pages (from-to)674-679
Number of pages6
JournalBiochimica et Biophysica Acta - Proteins and Proteomics
Issue number4
Publication statusPublished - 2009 Apr
Externally publishedYes


  • Ascidian
  • Redox
  • Thiol-disulfide exchange reaction
  • Vanabin2
  • Vanadium

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biophysics
  • Biochemistry
  • Molecular Biology


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