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Synthesis of activated pyrimidine ribonucleotides in prebiotically plausible conditions

机译：在益生元合理的条件下合成活化的嘧啶核糖核苷酸

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摘要

At some stage in the origin of life, an informational polymer must have arisen by purely chemical means. According to one version of the 'RNA world' hypothesis this polymer was RNA, but attempts to provide experimental support for this have failed. In particular, although there has been some success demonstrating that 'activated' ribonucleotides can polymerize to form RNA, it is far from obvious how such ribonucleotides could have formed from their constituent parts (ribose and nucleobases). Ribose is difficult to form selectively, and the addition of nucleobases to ribose is inefficient in the case of purines and does not occur at all in the case of the canonical pyrimidines. Here we show that activated pyrimidine ribonucleotides can be formed in a short sequence that bypasses free ribose and the nucleobases, and instead proceeds through arabinose amino-oxazoline and anhydronucleoside intermediates. The starting materials for the synthesis-cyanamide, cyanoacetylene, glycolaldehyde, glyceraldehyde and inorganic phosphate-are plausible prebiotic feedstock molecules, and the conditions of the synthesis are consistent with potential early-Earth geochemical models. Although inorganic phosphate is only incorporated into the nucleotides at a late stage of the sequence, its presence from the start is essential as it controls three reactions in the earlier stages by acting as a general acid/base catalyst, a nucleophilic catalyst, a pH buffer and a chemical buffer. For prebiotic reaction sequences, our results highlight the importance of working with mixed chemical systems in which reactants for a particular reaction step can also control other steps.
机译：在生命起源的某个阶段，信息聚合物必定是通过纯粹的化学手段产生的。根据“ RNA世界”假说的一种说法，这种聚合物是RNA，但是为此提供实验支持的尝试失败了。尤其是，尽管已经成功地证明了“活化的”核糖核苷酸可以聚合形成RNA，但如何从其组成部分（核糖和核碱基）形成这种核糖核苷酸还远不是很明显。核糖难以选择性地形成，并且对于嘌呤而言，向核糖添加核碱基效率低下，而对于标准嘧啶则根本不发生。在这里，我们显示活化的嘧啶核糖核苷酸可以在短序列中形成，绕过游离核糖和核苷碱基，而是通过阿拉伯糖氨基恶唑啉和脱水核苷中间体进行。合成的起始原料氰胺，氰基乙炔，乙醇醛，甘油醛和无机磷酸盐是可能的益生元原料分子，合成条件与潜在的早期地球化学模型一致。尽管无机磷酸盐仅在序列的后期被掺入核苷酸中，但是从一开始它的存在就至关重要，因为它通过充当一般的酸/碱催化剂，亲核催化剂，pH缓冲剂来控制较早阶段的三个反应和化学缓冲剂。对于益生元反应序列，我们的结果强调了使用混合化学系统的重要性，在混合化学系统中，特定反应步骤的反应物也可以控制其他步骤。

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  • 来源
    《Nature》 |2009年第7244期|239-242|共4页
  • 作者

    Matthew W. Powner; Beatrice Gerland; John D. Sutherland;

  • 作者单位

    School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK;

    School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK;

    School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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  • 正文语种 eng
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