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  • 用含有Zn离子,Mg离子打断RNA的原理是什么?

    Ajar 发布于:2016.09.29

    RNA fragmentation 

     
    2条评论 712浏览 邀请回答

    ACC-CAA-TGG 回答于:2016年10月12日 16:46:471楼

    上海 华东理工大学生物工程学院 生化与分子博士 

    The phosphodiester bonds in the covalent backbone of
    RNA are subject to slow, non-enzymatic cleavage through the “in-line” nucleophilic
    attack of the 2´ oxygen on the adjacent phosphorus center (see Fig. 1).
    When the 2´ oxygen, the phosphorus, and adjacent 5´ oxygen enter an “inline”
    conformation, the 2´ oxygen acts as a nucleophile in the intramolecular
    displacement of the 5´ oxygen in the adjacent phosphorus center and efficiently
    cleaves the RNA linkage. The relative speeds of spontaneous cleavage are
    dependent on local structural characteristics of each RNA linkage (see Fig. 2).
    Single-stranded RNA lacks secondary structure and is free to sample a range

     of conformations, including in-line geometry. Consequently, these linkages
    are susceptible to spontaneous cleavage through in-line attack. In contrast to
    flexible single-stranded RNA domains, linkages found in the highly structured
    regions of a folded RNA are locked into position. The linkages in these structured
    RNA regions are less likely to sample an in-line geometry and therefore
    have a reduced chance of cleaving. Occasionally, RNA secondary structure
    actually locks the molecule into an in-line conformation resulting in accelerated
    cleavage of the linkage involved (10). However, this is a rare occurrence and
    will only infrequently lead to misassignment of structured and unstructured
    RNA regions.

    ACC-CAA-TGG 回答于:2016年10月12日 16:58:112楼

    上海 华东理工大学生物工程学院 生化与分子博士 

    从文献里可以知道RNA本身会有一个非酶促的降解过程,通过氧原子的亲核进攻致使RNA磷酸二酯键断裂。该protocol中作者在反应时添加了Mg2+离子,在终止反应时加了EDTA,所以我觉得金属离子在这个过程扮演的应该是催化剂的角色。

    In-Line Probing Analysis of Riboswitches
    Elizabeth E. Regulski and Ronald R. Breaker


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