Kalek Marcin, Madsen Andreas S, Wengel Jesper
Nucleic Acid Center, Department of Physics and Chemistry, University of Southern Denmark, Odense M, Denmark.
J Am Chem Soc. 2007 Aug 1;129(30):9392-400. doi: 10.1021/ja071076z. Epub 2007 Jul 7.
Herein we describe the reversible changing of DNA duplex thermal stability by exploiting transition metal complexation phenomena. A terpyridine ligand was conjugated to the N2'-atoms of 2'-amino-2'-deoxyuridine and its locked counterpart 2'-amino-LNA, and these metal-complexing monomers were incorporated into oligodeoxyribonucleotides. Upon addition of varying amounts of transition metal ions, the thermal stability of DNA duplexes containing these terpyridine-functionalized units in different constitutions was affected to different degrees (DeltaTm values = -15.5 to +49.0 degrees C, relative to the unmodified duplex). The most pronounced effects were observed when two complexing monomers were positioned in opposite strands. Addition of 1 equiv of Ni2+ to such a system induced extraordinary duplex stabilization. Molecular modeling studies suggest, as an explanation for this phenomenon, formation of nickel-mediated interstrand linkages in the minor groove. Addition of an excess of metal ions resulted in largely decreased Tm values. Alternating addition of metal ions and EDTA demonstrated reversibility of metal ion-induced changes in hybridization strength, proving that the described approach provides an efficient method for duplex stability modulation.
在此，我们描述了通过利用过渡金属络合现象来可逆地改变DNA双链体的热稳定性。将三联吡啶配体与2'-氨基-2'-脱氧尿苷及其锁定类似物2'-氨基-LNA的N2'-原子共轭，然后将这些金属络合单体掺入寡脱氧核糖核苷酸中。加入不同量的过渡金属离子后，含有这些不同组成的三联吡啶功能化单元的DNA双链体的热稳定性受到不同程度的影响（相对于未修饰的双链体，ΔTm值 = -15.5至+49.0℃）。当两个络合单体位于相反链中时，观察到最明显的效果。向这样的体系中加入1当量的Ni2+会导致双链体异常稳定。分子建模研究表明，作为对这种现象的解释，在小沟中形成了镍介导的链间连接。加入过量的金属离子会导致Tm值大幅降低。交替加入金属离子和EDTA证明了金属离子诱导的杂交强度变化的可逆性，证明所描述的方法为双链体稳定性调节提供了一种有效的方法。
