The hammerhead cleavage reaction in monovalent cations
The hammerhead cleavage reaction in monovalent cations
复制标题
DOI：
10.1017/s1355838201002357
复制
发表时间：
2001-04-01
期刊：
影响因子：
4.5
通讯作者：
Bartel, DP
中科院分区：
文献类型：
--
作者：
Curtis, EA;Bartel, DP
最近，Murray等人（Chem Biol，1998，5：587-595）发现，如果在高浓度（大于或等于1 M）的单价离子中孵育，锤头状核酶不需要二价金属离子来获得活性。我们进一步表征了在不存在二价金属的情况下的锤头状切割反应。锤头是活跃的，在广泛的一价离子，和4 M Li+的速率增强只有20倍小于10 mM Mg 2+。在第I族单价金属中，速率以对数线性方式与离子半径相关。在10 mM Mg 2+、4 M Li+和4 M Na+中，反应的pH依赖性相似。交换惰性金属络合物Co（NH3）（6）（3+）也支持大量的锤头活性。这些结果表明，金属离子在反应中不作为碱，并且不同金属离子对锤头状裂解速率的影响主要反映了对催化的结构贡献。
Recently, Murray et al. (Chem Biol, 1998, 5:587-595) found that the hammerhead ribozyme does not require divalent metal ions for activity if incubated in high (greater than or equal to1 M) concentrations of monovalent ions. We further characterized the hammerhead cleavage reaction in the absence of divalent metal. The hammerhead is active in a wide range of monovalent ions, and the rate enhancement in 4 M Li+ is only 20-fold less than that in 10 mM Mg2+. Among the Group I monovalent metals, rate correlates in a log-linear manner with ionic radius, The pH dependence of the reaction is similar in 10 mM Mg2+, 4 M Li+, and 4 M Na+. The exchange-inert metal complex Co(NH3)(6)(3+) also supports substantial hammerhead activity. These results suggest that a metal ion does not act as a base in the reaction, and that the effects of different metal ions on hammerhead cleavage rates primarily reflect structural contributions to catalysis.