Physiochemical Study on Highly Selective Accumulation of Vanadium Ions by Ascidians

关于海鞘中的钒，人们已经知道了很多，海鞘也被称为被囊动物或海鞘。例如，在属于脉鳃亚目的芽状海鞘的血细胞中，钒的浓度达到350毫微克/毫升，这是大约10种血液中海水中钒浓度的10^7倍。虽然钒在海水中是+5氧化态（V^V），但几乎所有的钒都是通过+4氧化态（V^）被还原到+3氧化态（V <III>^）<IV>并储存在钒细胞的液泡中。本课题研究发现：从悉尼对虾（A.sydneiensis same）血细胞中提取的钒相关蛋白（VAP）每摩尔含16个钒原子;在多毛纲假眼溪蟹的沉淀蛋白中检测到与抗VAP的多克隆抗体识别的相同抗原，海鞘;本文报道了脱钒的VAP（apo-VAP），发现它能与10个钒原子结合，并测定了12.5kDa和15 kDa VAP基因的cDNA序列，从表达VAP基因的质粒载体转染的大肠杆菌中分离到融合蛋白，制备了特异性抗钒细胞空泡膜的单克隆抗体，并对VAP基因的表达进行了初步研究。发现磷酸戊糖途径中的G6 PDH、6PGDH和转酮醇酶以及糖原磷酸化酶存在于钒细胞的细胞质中;发现NADPH可将V^V-EDTA还原为V^<IV>-EDTA。

A lot is known about the vanadium in ascidians, which are also known as tunicates or sea squirts. For example, the concentration of vanadium attains 350 mMin the blood cells of Ascidia gemmata belonging to the suborder Phlebobranchia, which is l0^7times higher than the concentration in sea water among approximately ten types of blood. cells, signet ring cells are true vanadocytes, vanadium-containing blood cells, almost all vanadium is reduced to the +3 oxidation state (V^<III>) via the +4 oxidation state (V^<IV>) and stored in vacuoles of vanadocytes, although vanadium is in the +5 oxidation state (V^V) in seawater.We have revealed by the research project followings : a vanadium-associated protein (VAP) extracted from the blood cells of A.sydneiensis sames was revealed to contain 16 atoms of vanadium per a mol ; the same antigen recognized with a polyclonal antibody against VAP was detected in the precipitated proteins of the polychaete Pseudopotamilla occelata which was the first animal revealed to contain high levels of vanadium besides ascidians ; apo-VAP, VAP removed vanadium, was found to bind 10 atoms of vanadium ; the nucleotide sequences of cDNAs encoding 12.5 kDa and 15 kDa of VAPs are revealed ; a fusion protein was isolated from E.coil transfected with plasmid vector expressing VAPs genes ; a monoclonal antibody specific to vacuolar membrane of vanadocytes was prepared ; G6PDH, 6PGDH, and transketolase in the pentose phosphate pathway and glycogen phosphorylase were found to be in the cytoplasm of vanadocytes ; NADPH was revealed to reduce V^V-EDTA to V^<IV>-EDTA.