钚是一種對人體有毒的人造大分子,，現在,，研究人員深入分析了人體細胞吸收放射性钚元素的機理,，新成果發(fā)表在7月在線出版的《自然—化學生物學》期刊上,。

最近,，因大地震導致的日本福島核電站危機,，以及含钚燃料的核反應堆在日本之外的其他國家的使用,，新研究將有助于科學家們探索在暴露于钚污染的環(huán)境中，如何最小化人體細胞對钚的吸收量?？茖W家們指出,，钚具有鐵離子的部分化學性質，它會以細胞吸收營養(yǎng)礦物質通道被細胞吸收,。

Mark Jensen和同事指出,，情況確實如此，但有一個重要的附加條件,。攜帶鐵離子的蛋白質輸送器進入細胞的前提條件是這種蛋白質兩端與鐵離子鍵接的葉片能夠合攏,。不過，只有其中一個蛋白質葉片能與钚鏈接,，因此,，細胞吸收钚的條件是鏈接钚的蛋白質的另一端還必須鏈接鐵離子。(生物谷 Bioon.com)

doi:10.1038/nchembio.594
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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.