MOLECULAR-STRUCTURE OF AN A-DNA DECAMER D(ACCGGCCGGT)
MOLECULAR-STRUCTURE OF AN A-DNA DECAMER D(ACCGGCCGGT)
复制标题
DOI：
10.1111/j.1432-1033.1989.tb14724.x
复制
发表时间：
1989-05-01
期刊：
影响因子：
--
通讯作者：
WANG, AHJ
中科院分区：
文献类型：
--
作者：
FREDERICK, CA;QUIGLEY, GJ;WANG, AHJ
DNA 十聚体 d(ACCGGCCGGT) 的分子结构已通过 0.20 nm 处的单晶 X 射线衍射分析得到解析和精炼，最终 R 因子为 18.0%。十聚体结晶为 A-DNA 双螺旋片段，其晶胞尺寸为 a = b = 3.923 nm 和 c = 7.80 nm，位于空间群 P6122 中。这种 A-DNA 十聚体的整体构象与 A-DNA 的纤维模型非常相似，后者具有较大的平均碱基对倾斜度，因此具有宽而浅的小凹槽。该结构与几种 A-DNA 八聚体的结构形成对比，其中分子均具有低碱基对倾斜角（8-12°），导致外观介于 B-DNA 和 A-DNA 之间。该十聚体的平均螺旋参数是 A-DNA 的典型螺旋参数，每圈螺旋 10.9 个碱基对，平均螺旋扭转角为 33.1°，碱基对倾斜角为 18.2°。但是，该分子中的 CpG 步骤具有 24.5°的低局部扭转角，与其他 A-DNA 寡聚物中看到的类似，因此似乎是内在的堆叠模式 对于这一步。分子使用重复的结合基序堆积在晶体中，即一个螺旋的末端碱基对邻接另一个螺旋的浅小沟的表面。此外，与大多数其他 A-DNA 结构不同，GC 碱基对具有较大的螺旋桨扭转角。
The molecular structure of the DNA decamer d(ACCGGCCGGT) has been solved and refined by single-crystal X-ray-diffraction analysis at 0.20 nm to a final R-factor of 18.0%. The decamer crystallizes as an A-DNA double helical fragment with unit-cell dimensions of a = b = 3.923 nm and c = 7.80 nm in the space group P6122. The overall conformation of this A-DNA decamer is very similar to that of the fiber model for A-DNA which has a large average base-pair tilt and hence a wide and shallow minor groove. This structure is in contrast to that of several A-DNA octamers in which the molecules all have low base-pair-tilt angles (8-12.degree.) resulting in an appearance intermediate between B-DNA and A-DNA. The average helical parameters of this decamer are typical of A-DNA with 10.9 base pairs/turn of helix, an average helical twist angle of 33.1.degree., and a base-pair-tilt angle of 18.2.degree.. However, the CpG step in this molecule has a low local-twist angle of 24.5.degree., similar to that seen in other A-DNA oligomers, and therefore appears to be intrinsic stacking pattern for this step. The molecules pack in the crystal using a recurring binding motif, namely, the terminal base pair of one helix abuts the surface of the shallow minor groove of another helix. In addition, the GC base pairs have large propeller-twist angles, unlike those found most other A-DNA structures.