Sm(iii)[12-MCGa(III)shi-4] as a luminescent probe for G-quadruplex structures†,Metallomics

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Sm(iii)[12-MCGa(III)shi-4] as a luminescent probe for G-quadruplex structures†
Metallomics ( IF 2.9 ) Pub Date : 2017-11-15 00:00:00 , DOI: 10.1039/c7mt00232g
Ewa Rajczak _{1,

2,

3,

4} , Vincent L. Pecoraro _{5,

6,

7,

8} , Bernard Juskowiak _{1,

2,

3,

4}

Affiliation

G-quadruplexes (GQs), spatial assemblies of guanine-rich DNA strands, play an important role in the regulation of gene expression and chromosome stabilization. These structures are recognized to be useful in cancer therapies as the presence of multiple G-quadruplexes in a telomeric strand stops cancer cell proliferation. Metallacrowns of the type 12-MC-4 form planar structures that have remarkable similarity to G-tetrads in terms of dimension, shape and the ability to bind alkali metal and lanthanide cations in a central cavity. The interaction between the Sm(III)[12-MC_Ga(III)shi-4] (SmMC) metallacrown (MC) and human telomeric G-quadruplex structures was examined using several methods including CD titrations, CD melting temperatures, fluorescence titration of SmMC with GQ/Na⁺, fluorescence intercalator displacement (FID) assays and methods measuring the MC quenching effect on the Tb³⁺/GQ luminescence. It was proven that the studied metallacrown acted as a sensing probe and interacted with quadruplex DNA. The Stern–Volmer quenching constant (K_as) of Tb³⁺/GQ luminescence was calculated to be 3.9 × 10⁵ M⁻¹. The binding constant using the indirect FID method gave the result of 1.3 × 10⁵ M⁻¹. CD melting temperature experiments reveal the following pattern – the higher the concentration of the complex the lower the registered T_m for quadruplex DNA, which indicates a destabilizing effect of SmMC at higher GQ : MC ratios. These data implicate a shape and size selective interaction between MCs and GQs that may be exploited for telomere detection.

中文翻译：

Sm（iii）[12-MC _{Ga（III）shi} -4]作为G-四链体结构的发光探针†

G-四链体（GQs）是富含鸟嘌呤的DNA链的空间组装，在调节基因表达和染色体稳定中起重要作用。这些结构被认为可用于癌症治疗，因为端粒链中存在多个G-四链体可阻止癌细胞增殖。12-MC-4型金属漆form形成的平面结构在尺寸，形状以及在中心腔体中结合碱金属和镧系元素阳离子的能力方面与G-tetrads具有显着的相似性。Sm（III）[12-MC _{Ga（III）shi} -4]（SmMC）金属内分泌（MC）与人端粒G-四链体结构之间的相互作用使用CD滴定法，CD熔解温度，荧光滴定法等几种方法进行了研究。具有GQ / Na的SmMC⁺，荧光嵌入剂置换（FID）分析和方法，用于测量MC对Tb³⁺ / GQ发光的猝灭作用。事实证明，所研究的金属催乳素可作为传感探针并与四链体DNA相互作用。Tb³⁺ / GQ发光的斯特恩-沃尔默猝灭常数（ K _as）经计算为3.9×10⁵ M^-1。使用间接FID方法的结合常数得到1.3×10⁵ M^-1的结果。CD熔化温度实验揭示了以下模式–配合物浓度越高，记录的T _m越低对于四链体DNA而言，这表明SmMC在较高的GQ：MC比率下具有去稳定作用。这些数据暗示了可用于端粒检测的MC和GQ之间的形状和大小选择性相互作用。

更新日期：2017-11-15

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