Müller J, Drumm M, Boudvillain M, Leng M, Sletten E, Lippert B
Fachbereich Chemie, Universität Dortmund, Germany.
J Biol Inorg Chem. 2000 Oct;5(5):603-11. doi: 10.1007/s007750000143.
The oligonucleotides 5'-d(TTTTCTTTTG) and 5'-d(AAAAGAAAAG) were cross-linked with a trans-[Pt(NH3)2]2+ entity via the N7 positions of the 3'-end guanine bases to give parallel-stranded (ps) DNA. At pH 4.2, CD and NMR spectroscopy indicate the presence of Hoogsteen base pairing. In addition, temperature-dependent UV spectroscopy shows an increase in melting temperature for the platinated duplex (35 degrees C) as compared to the non-platinated, antiparallel-stranded duplex formed from the same oligonucleotides (21 degrees C). A monomer-dimer equilibrium for the platinated 20mer is revealed by gel electrophoresis. At pH 4.2, addition of a third strand of composition 5'-d(AGCTTTTCTTTTAG) to the ps duplex leads to the formation of a triple helix with two distinct melting points at 38 degrees C (platinum cross-linked Hoogsteen part) and 21 degrees C (Watson-Crick part), respectively.
寡核苷酸5'-d(TTTTCTTTTG)和5'-d(AAAAGAAAAG)通过3'-末端鸟嘌呤碱基的N7位与反式-[Pt(NH3)2]2+实体交联，形成平行链(ps)DNA。在pH 4.2时，圆二色光谱(CD)和核磁共振光谱(NMR)表明存在Hoogsteen碱基对。此外，温度依赖紫外光谱显示，与由相同寡核苷酸形成的未铂化的反平行链双链体(21℃)相比，铂化双链体的解链温度升高(35℃)。凝胶电泳揭示了铂化20聚体的单体-二聚体平衡。在pH 4.2时，向ps双链体中加入第三条组成5'-d(AGCTTTTCTTTTAG)的链，导致形成三链螺旋，其在38℃(铂交联的Hoogsteen部分)和21℃(沃森-克里克部分)分别有两个不同的解链温度。
