STRUCTURES OF THE MISMATCHED DUPLEX D(GGGTGCCC) AND ONE OF ITS WATSON-CRICK ANALOGS D(GGGCGCCC)
STRUCTURES OF THE MISMATCHED DUPLEX D(GGGTGCCC) AND ONE OF ITS WATSON-CRICK ANALOGS D(GGGCGCCC)
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DOI：
10.1016/0022-2836(88)90340-3
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发表时间：
1988-03-05
影响因子：
5.6
通讯作者：
SHAKKED, Z
中科院分区：
文献类型：
--
作者：
RABINOVICH, D;HARAN, T;SHAKKED, Z
合成了错配双链体d（GGGTGCCC）（I）及其两个Watson-Crick类似物（dGGGCGCCC）（II）和d（GGTACC）（III）。在2.5和1.7埃的分辨率下测定（I）和（II）的X射线晶体结构。（1. = 0.1 nm），并分别细化到15和16%的R因子。(I)和（II）分别在空间群P61和P43212中结晶为A-DNA双螺旋八聚体，并且在室温下稳定。（I）的中心两个G.T错对采用如在其它G. T不匹配。这两种结构在螺旋中心区域的局部构象特征以及某些全局构象特征上存在显著差异。特别地，T-G采用大的螺旋扭曲（44 °）。而C-G采用小的（24 °）。).这种差异可以根据简单的几何考虑加以合理化。计算的两个双链体的碱基对堆积能表明（I）相对于（II）是不稳定的。通过紫外吸收分光光度法对三种低聚物中的每一种进行螺旋线圈转变测量。结果表明，用紫外分光光度法测得了三种齐聚物.结果表明，双链体的稳定性和跃迁的协同性依次为：（I）<（III）<（II）.这些研究可能有助于理解为什么DNA的某些区域比其他区域更容易发生自发突变。
The mismatched duplex d(GGGTGCCC) (I) and its two Watson-Crick analogues (dGGGCGCCC) (II) and d(GGTACC) (III) were synthesized. The X-ray crystal structures of (I) and (II) were determined at resolutions of 2.5 and 1.7 .ANG. (1 .ANG. = 0.1 nm) and refined to R factors of 15 and 16%, respectively. (I) and (II) crystalize as A-DNA double-helical octamers in space groups P61 and P43212, respectively, and are stable at room temperature. The central two G.T mispairs of (I) adopt the wobble geometry as observed in other G .cntdot. T mismatches. The two structures differ significanlty in their local conformational features at the central helical regions as well as in some global ones. In particular, T-G adopts a large helical twist (44.degree.) whereas C-G adopts a small one (24.degree. ). This difference can be rationalized on the basis of simple geometrical considerations. Base-pair stacking energies which were calculated for the two duplexes indicate that (I) is destabilized with respect to (II). Helix-coil transition measurements were performed for each of the three oligomers by means of ultraviolet absorbance spectrophotometry. The results indicate three oligomers by means of ultraviolet absorbance spectrophotometry. The results indicate that the stability of the duplexes and the co-operativity of the transition are in the following order: (I) < (III) < (II). Such studies may help in understanding why certain regions of DNA are more likely to undergo spontaneous mutations than others.