Nejedlý K, Sýkorová E, Diekmann S, Palecek E
Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
Biophys Chem. 1998 Jul 27;73(3):205-16. doi: 10.1016/s0301-4622(98)00145-8.
Complex of osmium tetroxide and bipyridine (Os,bipy), KMnO4, and diethyl pyrocarbonate (DEPC) were used to probe curved DNA at single nucleotide resolution. The DNA was constructed from repeated dAn:dTn-blocks with dATATA and dAGAGA interblock sequences. The DNA was probed in the linear and supercoiled form at various salt concentrations. While all purines were available for DEPC attack, the thymines within the blocks were resistant to chemical probing by KMnO4 and Os,bipy. Only the 3'-flanking dTs were available for modification. The thymines within dTC and dTA sequences showed modification indicating that these thymines display an unstacked structure allowing both probes to attack. Under destabilizing conditions, at low ionic strength and superhelical stress, considerable unstacking was observed. We found experimental indications that under these destabilizing conditions unpaired regions might appear, probably within the dATATA sequence.
四氧化锇与联吡啶复合物（Os,bipy）、高锰酸钾（KMnO4）和焦碳酸二乙酯（DEPC）被用于以单核苷酸分辨率探测弯曲的DNA。该DNA由重复的dAn:dTn块构建而成，块间序列为dATATA和dAGAGA。在不同盐浓度下，分别以线性和超螺旋形式对该DNA进行探测。虽然所有嘌呤均可被DEPC攻击，但块内的胸腺嘧啶对KMnO4和Os,bipy的化学探测具有抗性。只有3'侧翼的dT可被修饰。dTC和dTA序列内的胸腺嘧啶显示出修饰，表明这些胸腺嘧啶呈现出未堆积的结构，使得两种探针均可攻击。在不稳定条件下，即在低离子强度和超螺旋应力下，观察到相当程度的未堆积现象。我们发现实验迹象表明，在这些不稳定条件下，可能会出现未配对区域，很可能出现在dATATA序列内。
