Structure and photoinduced electron transfer in exceptionally stable synthetic DNA hairpins with stilbenediether linkers
Structure and photoinduced electron transfer in exceptionally stable synthetic DNA hairpins with stilbenediether linkers
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DOI：
10.1021/ja991934u
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发表时间：
1999-10-27
影响因子：
15
通讯作者：
Egli, M
中科院分区：
文献类型：
--
作者：
Lewis, FD;Liu, XY;Egli, M
已知BIS(寡核苷酸)与连接短互补寡核苷酸的合成连接物形成合成DNA或RNA发夹，在某些情况下，它们比具有寡核苷酸连接物的天然发夹更稳定。1，2我们在这里报道了具有二苯二醚(SE)连接基的偶联物(图1)形成非常稳定的(聚)DT-SE-(聚)da发夹。SE-桥联发夹的晶体结构证实它采用二苯乙烯与相邻碱基对π-堆叠的B型结构。二苯乙烯二醚还介导了不同于通常在DNA晶体中发现的新的晶格相互作用。二苯乙烯醚的单重态激发态是一个强的电子给体，可被邻近的dt-da或dc-dg碱基对作为电子受体而迅速猝灭。这一行为与具有二苯二甲酰胺连接体(SA，图1)的偶联物的行为是互补的，该连接体充当电子受体。3，4共轭化合物1-7显示一个长波长吸收带(λmax)32 7 nm，归属于二苯乙烯的π，π*跃迁和一个较短的波长带(λmax)2 60 nm，归属于重叠的二苯乙烯和碱基吸收带。在含0.1M氯化钠的水溶液中加热时，共轭化合物1-7的260 nm谱带表现出吸光度的增加(减色)。4的CD谱在283 nm处有一个正带，在250 nm处有一个负带，这与在溶液中形成的B型DNA结构一致。4的32 7 nm吸收带与Se2在甲醇中的吸收峰(λmax)32 4 nm相似，既没有减色现象，也没有诱导的圆二色谱.
Bis (oligonucleotide) conjugates with synthetic linkers connecting short complementary oligonucleotides are known to form synthetic DNA or RNA hairpins which are, in some cases, more stable than natural hairpins which possess oligonucleotide linkers. 1, 2 We report here that conjugates possessing stilbenediether (SE) linkers (Chart 1) form exceptionally stable (poly) dT-SE-(poly) dA hairpins. The crystal structure of a SE-bridged hairpin confirms that it adopts a B-form structure in which the stilbene is π-stacked with the adjacent base pair. The stilbenediether also mediates novel lattice interactions that are distinct from those normally found in DNA crystals. The singlet excited state of the stilbenediether is a strong electron donor which is rapidly quenched by either neighboring dT-dA or dC-dG base pairs which function as electron acceptors. This behavior is complementary to that of conjugates possessing a stilbenedicarboxamide linker (SA, Chart 1), which serves as an electron acceptor. 3, 4 The conjugates 1-7 display a long wavelength absorption band (λmax) 327 nm) assigned to the stilbene π, π* transition and a shorter wavelength band (λmax) 260 nm) assigned to overlapping stilbene and nucleobase absorption bands. The 260 nm bands of conjugates 1-7 display an increase in absorbance (hypochromism) upon heating in aqueous buffer containing 0.1 M NaCl. The thermal dissociation profiles provide melting temperatures which are reported in Chart 1. The CD spectrum of 4 has a positive band at 283 nm and a negative band at 250 nm, consistent with formation of a B-form DNA structure in solution. The 327 nm absorption band for 4 is similar in appearance to that of SE2 in methanol (λmax) 324 nm) and displays neither hypochromism nor induced circular dichroism.