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

作者：Kawakami Norifumi; Ueki Tatsuya; Amata Yusuke; Kanamori Kan; Matsuo Koichi; Gekko Kunihiko; Michibata Hitoshi^*

来源：Biochimica et Biophysica Acta-Proteins and Proteomics, 2009, 1794(4): 674-679.

DOI：10.1016/j.bbapap.2009.01.007

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

The unusual ascidian ability to accumulate high levels of vanadium ions at concentrations of up to 350 mM, a 10(7)-fold increase over that found in seawater, has been attracting interdisciplinary attention for a century. Accumulated V(V) is finally reduced to V(III) via V(IV) 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 V(V) to V(IV). 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 thioldisulfide exchange reactions.

• 出版日期2009-4