Zhang Haiyuan, Yu Haijia, Ren Jinsong, Qu Xiaogang
Division of Biological Inorganic Chemistry, Key Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Graduate School of the Chinese Academy of Sciences, Changchun, Jilin 130022, China.
Biophys J. 2006 May 1;90(9):3203-7. doi: 10.1529/biophysj.105.078402. Epub 2006 Feb 10.
We report here that a cubane-like europium-L-aspartic acid complex at physiological pH can discriminate between DNA structures as judged by the comparison of thermal denaturation, binding stoichiometry, temperature-dependent fluorescence enhancement, and circular dichroism and gel electrophoresis studies. This complex can selectively stabilize non-B-form DNA polydApolydT but destabilize polydGdCpolydGdC and polydAdTpolydAdT. Further studies show that this complex can convert B-form polydGdCpolydGdC to Z-form under the low salt condition at physiological temperature 37 degrees C, and the transition is reversible, similar to RNA polymerase, which turns unwound DNA into Z-DNA and converts it back to B-DNA after transcription. The potential uses of a left-handed helix-selective probe in biology are obvious. Z-DNA is a transient structure and does not exist as a stable feature of the double helix. Therefore, probing this transient structure with a metal-amino acid complex under the low salt condition at physiological temperature would provide insights into their transitions in vivo and are of great interest.
我们在此报告，在生理pH值下，一种类似立方烷的铕-L-天冬氨酸络合物通过热变性、结合化学计量学、温度依赖性荧光增强以及圆二色性和凝胶电泳研究的比较，可以区分不同的DNA结构。这种络合物可以选择性地稳定非B型DNA多聚腺苷酸多聚胸苷酸，但会使多聚鸟苷酸多聚胞苷酸和多聚腺苷酸多聚腺苷酸不稳定。进一步的研究表明，在生理温度37摄氏度的低盐条件下，这种络合物可以将B型多聚鸟苷酸多聚胞苷酸转化为Z型，并且这种转变是可逆的，类似于RNA聚合酶，它在转录后将解开的DNA转化为Z-DNA并再转化回B-DNA。左手螺旋选择性探针在生物学中的潜在用途是显而易见的。Z-DNA是一种瞬时结构，不作为双螺旋的稳定特征存在。因此，在生理温度的低盐条件下用金属-氨基酸络合物探测这种瞬时结构将有助于深入了解它们在体内的转变，并且具有极大的研究价值。
