DNA FLEXIBILITY STUDIED BY COVALENT CLOSURE OF SHORT FRAGMENTS INTO CIRCLES
DNA FLEXIBILITY STUDIED BY COVALENT CLOSURE OF SHORT FRAGMENTS INTO CIRCLES
复制标题
DOI：
10.1073/pnas.78.8.4833
复制
发表时间：
1981-01-01
期刊：
影响因子：
--
通讯作者：
BALDWIN, RL
中科院分区：
文献类型：
--
作者：
SHORE, D;LANGOWSKI, J;BALDWIN, RL
我们测量了含有EcoRI内聚末端的限定序列的DNA限制性片段的环闭合概率（j因子），其大小范围为126-4361碱基对（bp）。j因子被定义为环化和通过内聚末端的双分子缔合的平衡常数之比。与T4 DNA连接酶对内聚末端的共价关闭相比，末端连接反应速度快。在环化和生物分子结合反应中，连接酶的关闭速率与具有连接内聚末端的DNA分子的平衡分数成正比。j因子在242 ~ 4361 bp之间变化< 10倍；在242 ~ 126 bp之间，当DNA达到持续长度的大小范围（150 bp）时，其强度下降了100倍。关于环闭合，短的DNA片段具有惊人的灵活性。这些数据与其他人对虫状链闭合概率的预测很好地吻合。
The ring closure probability, or j factor, was measured for DNA restriction fragments of defined sequence bearing EcoRI cohesive ends and ranging in size from 126-4361 base pairs (bp). The j factor is defined as the ratio of the equilibrium constants for cyclization and for bimolecular association via the cohesive ends. The end-joining reactions are fast compared to covalent closure of the cohesive ends by T4 DNA ligase. The rate of ligase closure is shown to be proportional to the equilibrium fraction of DNA molecules with joined cohesive ends, both in cyclization and biomolecular association reactions. The j factor changes by < 10-fold between 242 and 4361 bp; it decreases by > 100-fold between 242 and 126 bp as the DNA reaches the size range of the persistence length (150 bp). As regards ring closure, short DNA fragments are surprisingly flexible. These data are in good agreement with predictions by others for the ring closure probability of a wormlike chain.