Circular dichroism of two conformations of poly[d(G-C)] induced by low pH.
Circular dichroism of two conformations of poly[d(G-C)] induced by low pH.
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低pH诱导的聚[d(G-C)]两种构象的圆二色性。
DOI：
10.1093/nar/14.24.10091
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发表时间：
1986
影响因子：
14.9
通讯作者：
Ratliff,RL
中科院分区：
文献类型：
--
作者：
Antao,VP;Gray,CW;Gray,DM;Ratliff,RL
圆二色性（CD）和紫外吸收数据表明，聚[d（G-C）]（在0.09M NaCl，0.01M Na+（磷酸盐），20°C下）在通过加入HCl降低pH时经历两个构象转变。第一次转变在约pH 3.0时完成。当pH降低至2.6或当温度升高至约40°C（pH 3.0）时，第二转变完成。在任一转变期间均无变性迹象。第二种酸性构象的CD谱具有较大的CD带，包括在288 nm处的一个阳性CD带，这是与C-CT+碱基对相关的特征。电子显微镜显示，没有显着的凝聚的超分子聚集体的形成对应于第一或第二酸形式的聚-[d（G-C）]。光谱数据，电子显微镜，质子吸收测量的基础上，我们提出了模型的二级结构，聚[d（G-C）]在其两个酸构象。
Circular dlchroism (CD) and UV absorption data qhowed that poly[d(G-C)] (at 0.09M NaCl, 0.01M Na+(phosphate), 20°C) underwent two conformatlonal transitions upon lowering of the pH by the addition of HC1. The first transition was complete at about pH 3.0. The second transition was complete upon lowering the pH to 2.6 or upon raising the tenperature, at pH 3.0, to about 40°C. There was no indication of denaturation during either transition. The CD spectrun for the second acid conformation had large CD bands including a positive one at 288nm, a characteristic associated with C-CT+base-pairs. Electron microscopy showed no significant formation of condensed supra-molecular aggregates corresponding to the first or second acid forms of poly-[d(G-C)]. On the basis of spectral data, electron microscopy, and proton-uptake measurements, we propose models for the secondary structures that poly[d(G-C)] adopts in its two acid conformations.