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[求助]
帮忙翻译一下下面的一段话
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本人不是学化学的，对该方面的知识不懂，请虫友帮忙。谢谢！ First, the phosphodiester linkage in RNA is coordinated to one of the metal ions in the cluster. This complex formation increases the electrophilicity of the phosphorus atom. Then, the hydroxide ion bound to the cluster activates the 2'-OH of RNA as a general base catalyst and promotes its intramolecular nucleophilic attack towards the phosphorus atom. The decrease in the energy barrier for the formation of the pentacoordinated intermediate (AG2 in Fig. 7) is mainly due to these factors. On decomposition of the resultant intermediate to the products, the coordination water on one of the metal ions (or the metal ion itself) functions as a general acid catalyst and stabilizes the leaving group. The 5'-alkoxide ion of ribose is otherwise too unstable to be removed. It is also plausible that the acid catalysis and the base catalysis take place concertedly, rather than in a stepwise manner, as described above |
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2楼2007-08-22 17:20:08