Study of a highly selective leaching of rare metals from seawater using biological functions

点击翻译按钮获取中文摘要

Rare metals such as vanadium, cobalt, manganese, nickel and molybdenum are dissolved in sea water at very low levels. Ascidians, especially belonging to the Phlebobranchia, are known to selectively accumulate high levels of vanadium. We previously extracted vanadium-associated proteins from vanadium-containing blood cells (vanadocytes) of Ascidia sydneiensis samea. In this study, full-length of cDNAs, encoding 12.5 kDa and 15 kDa vanadium-associated proteins (designated newly as Vanabin), respectively, which might have a clue to resolve the mechanism of vanadium accumulation, was analyzed. As a result, Vanabin was disclosed to consist of about 120 amino acids in which the content of cysteine residues is very high and to be a novel protein having α-helix. Recombinant Vanabin was found to bind with about 20 atoms of vanadium ions and its binding constant is 10^<-7>M. Metal binding sites in progress.Recently, it has been disclosed that 12.5 kDa Vanabin binds with about 10 atoms of vanadium in the +4 oxidation state, 15 kDa Vanabin does not bind with iron ions or copper ions and copper ions inhibits the binding of Vanabin with vanadium ions, competitively.