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首页> 外文期刊>Chemistry: A European journal >Sequence-Selective Metalation of Double-Helical Oigodeoxyribonucleotides with Pt~(III), Mn~(II), and Zn~(II) Ions
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Sequence-Selective Metalation of Double-Helical Oigodeoxyribonucleotides with Pt~(III), Mn~(II), and Zn~(II) Ions

机译：具有Pt〜（III），Mn〜（II）和Zn〜（II）离子的双螺旋寡聚脱氧核糖核苷酸的序列选择金属化

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摘要

Reactions of [PtCl(dien)]~+ (dien = diethylenetriamine), Mn~(2+) and Zn~(2+) ions with three different double-helical oligodeoxyribonucleotides, which contain the central sequence GGXY (XY = AT, TA or CC) have been monitored by NMR spectroscopy. 2D [~1H, ~(15)H] HSQC/HMQC NMR spectroscopy using ~(15)N-labeled Pt(dien) show that the rate of formation of 3'-G-N7 and 5'-G-N7 platinated adducts is highly sequence dependent. The relative rates of platination of 5'-G versus 3'-G are largest for the sequence -GGCC-, for which only a small fraction of the 3'-G adduct is formed; for -GGTA-, the rate of 5'-G platination is about eight times that of 3'-G, and for -GGAT- the ratio is 1.2. These values are in qualitative agreement with those obtained for G-N7/Mn~(2+) selectivity as determined by paramagnetic line broadening of the adjacent G-H8, and also G-N7/Zn~(2+) selectivity as determined by G-H8 chemical shift changes. Fluctuation in the nucleophilicity of G-N7 may be explained by variation of the pi-stacking interaction between base residues along the double helix. The reaction mixtures containing platinated 3'-G and 5'-G fractions were separated by HPLC. Since the duplexes are self-complementary, the platinated single strands were readily annealed to duplexes with two-fold symmetry and analyzed by 2D [~1H, ~1H] NOESY NMR spectroscopy. Unexpectedly, the 5'-G-H8 resonance signals of both 5'-G and 3'-G platinated duplexes showed large downfield shifts in the range delta = 0.3-0.6 ppm, while the 3'-G-H8 resonance signals in both cases exhibited no, or only slight, upfield shifts. Resonance signals for several other proteons in the central region undergo large chemical sift variations induced by platination, indicating that monofunctional binding to DNA leads to appreciable conformational changes.
机译：[PtCl（dien）]〜+（dien =二亚乙基三胺），Mn〜（2+）和Zn〜（2+）离子与三个不同的双螺旋寡聚脱氧核糖核苷酸的反应，它们包含中心序列GGXY（XY = AT，TA或CC）已通过NMR光谱监测。使用〜（15）N标记的Pt（dien）进行的2D [〜1H，〜（15）H] HSQC / HMQC NMR光谱表明，形成3'-G-N7和5'-G-N7铂加合物的速率与序列高度相关。对于序列-GGCC-，5'-G对3'-G的相对电镀速率最大，对于该序列，仅形成了3'-G加合物的一小部分。对于-GGTA-，5'-G的电镀速度约为3'-G的八倍;对于-GGAT-，该比率为1.2。这些值与通过相邻G-H8的顺磁性线展宽确定的G-N7 / Mn〜（2+）选择性以及通过确定的G-N7 / Zn〜（2+）选择性获得的定性一致。 G-H8化学位移发生变化。 G-N7亲核性的波动可以通过沿双螺旋的碱基残基之间的pi堆积相互作用的变化来解释。通过HPLC分离含有铂化的3'-G和5'-G级分的反应混合物。由于双链体是自互补的，因此镀铂单链易于退火成具有两倍对称性的双链体，并通过2D [〜1H，〜1H] NOESY NMR光谱分析。出乎意料的是，5'-G和3'-G镀铂双链体的5'-G-H8共振信号在δ= 0.3-0.6 ppm范围内均显示出大的下场偏移，而两个平台中的3'-G-H8共振信号病例没有或仅有轻微的高场移位。中心区域中其他几种蛋白质的共振信号经历了较大的化学筛分变化（由电镀引起），表明与DNA的单官能结合导致明显的构象变化。

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