科学家分析人体细胞吸收钚的机理

上一篇 / 下一篇  2011-08-31 11:30:56

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钚是一种对人体有毒的人造大分子,现在,研究人员深入分析了人体细胞吸收放射性钚元素的机理,新成果发表在7月在线出版的《自然—化学生物学》期刊上。

最近,因大地震导致的日本福岛核电站危机,以及含钚燃料的核反应堆在日本之外的其他国家的使用,新研究将有助于科学家们探索在暴露于钚污染的环境中,如何最小化人体细胞对钚的吸收量。科学家们指出,钚具有铁离子的部分化学性质,它会以细胞吸收营养矿物质通道被细胞吸收。

Mark Jensen和同事指出,情况确实如此,但有一个重要的附加条件。携带铁离子的蛋白质输送器进入细胞的前提条件是这种蛋白质两端与铁离子键接的叶片能够合拢。不过,只有其中一个蛋白质叶片能与钚链接,因此,细胞吸收钚的条件是链接钚的蛋白质的另一端还必须链接铁离子。

 

 

PMC:
PMID:

An iron-dependent and transferrin-mediated cellular uptake pathway for plutonium

Mark P Jensen; Drew Gorman-Lewis; Baikuntha Aryal; Tatjana Paunesku; Stefan Vogt; Paul G Rickert; Soenke Seifert; Barry Lai; Gayle E Woloschak; L Soderholm

Plutonium is a toxic synthetic element with no natural biological function, but it is strongly retained by humans when ingested. Using small-angle X-ray scattering, receptor binding assays and synchrotron X-ray fluorescence microscopy, we find that rat adrenal gland (PC12) cells can acquire plutonium in vitro through the major iron acquisition pathway—receptor-mediated endocytosis of the iron transport protein serum transferrin; however, only one form. of the plutonium–transferrin complex is active. Low-resolution solution models of plutonium-loaded transferrins derived from small-angle scattering show that only transferrin with plutonium bound in the protein's C-terminal lobe (C-lobe) and iron bound in the N-terminal lobe (N-lobe) (PuCFeNTf) adopts the proper conformation for recognition by the transferrin receptor protein. Although the metal-binding site in each lobe contains the same donors in the same configuration and both lobes are similar, the differences between transferrin's two lobes act to restrict, but not eliminate, cellular Pu uptake.


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