Characterization of the cation and temperature dependence of DNA quadruplex hydrogen bond properties using high-resolution NMR
Characterization of the cation and temperature dependence of DNA quadruplex hydrogen bond properties using high-resolution NMR
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DOI：
10.1021/ja0540369
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发表时间：
2005-10-19
影响因子：
15
通讯作者：
Feigon, J
中科院分区：
文献类型：
--
作者：
Dingley, AJ;Peterson, RD;Feigon, J
Oxy-1.5 DNA鸟嘌呤四链体的氢键网络的变化已经通过Na（+）-、K（+）-和NH（4）（+）-结合形式的反式氢键标量偶联（h2）J（N2 N7）在5 - 55 ℃的温度范围内进行了监测。（h ~ 2）J（N ~ 2N ~ 7）偶合的变化趋势为Na（+）> K（+）> NH（4）（+），并与不同阳离子位置和N ~ 2-H ~ 2 ~（2+）有关。N7相应结构中的H-键长。随着温度的升高，三种DNA四链体的（h2）J（N2 N7）耦合整体减弱，同时受体（15）N（7）化学位移整体增加。在35 ℃以上，光谱不均匀性表明Na（+）结合形式的热变性，而K（+）-和NH（4）（+）-配位形式的光谱均匀性持续到55 ℃。（h2）J（N2 N7）偶联的平均相对变化量与0.8 × 10（-3）/K相似，因此显著小于核酸双链体报告的相应值。DNA四链体中氢键几何构型的显着更高的热稳定性可以通过它们的G-四重态的阳离子配位和四条链之间广泛的氢键网络来合理化。对单个（h2）J（N2 N7）偶联的详细分析表明，包含碱基对G1 -G9* 和G4*-G1的5'链末端是所有三种阳离子结合形式的DNA四链体中最不耐热的区域。
Variations in the hydrogen bond network of the Oxy-1.5 DNA guanine quadruplex have been monitored by trans-H-bond scalar couplings, (h2)J(N2N7), for Na(+)-, K(+)-, and NH(4)(+)-bound forms over a temperature range from 5 to 55 degrees C. The variations in (h2)J(N2N7) Couplings exhibit an overall trend of Na(+) > K(+) > NH(4)(+) and correlate with the different cation positions and N2-H2... N7 H-bond lengths in the respective structures. A global weakening of the (h2)J(N2N7) couplings with increasing temperature for the three DNA quadruplex species is accompanied by a global increase of the acceptor (15)N(7) chemical shifts. Above 35 degrees C, spectral heterogeneity indicates thermal denaturation for the Na(+)-bound form, whereas spectral homogeneity persists up to 55 degrees C for the K(+)- and NH(4)(+)-coordinated forms. The average relative change of the (h2)J(N2N7) couplings amounts to similar to 0.8 x 10(-3)/K and is thus considerably smaller than respective values reported for nucleic acid duplexes. The significantly higher thermal stability of H-bond geometries in the DNA quadruplexes can be rationalized by their cation coordination of the G-quartets and the extensive H-bond network between the four strands. A detailed analysis of individual (h2)J(N2N7) couplings reveals that the 5' strand end, comprising base pairs G1 -G9* and G4*-G1, is the most thermolabile region of the DNA quadruplex in all three cation-bound forms.