摘要
对鸟嘌呤碱基G重复序列之间连接环结构对G-四链体形成的影响进行了研究。发现在连接环较长,DNA链不易形成G-四链体的情况下,可以通过将环序列设计成双链结构的方式促进G-四链体的重新形成。这就为传感器的设计提供了一个新途径,即可以利用目标分子对环部双链的调节作用控制G-四链体DNA酶的活性。为证明这一点,在双链区域引入T-T碱基错配,破坏双链结构使DNA链不能形成G-四链体。Hg2＋对T-T错配的稳定作用可以促进双链结构的形成,DNA链重新折叠成G-四链体,得到的G-四链体与氯化血红素（ Hemin）结合后形成具有过氧化物酶活性的G-四链体DNA酶,据此构建了Hg2＋传感器。利用此传感器可在10～700 nmol/L范围内实现Hg2＋的定量检测,检出限为8.7 nmol/L。在此基础上,利用半胱氨酸可以将Hg2＋从T-Hg2＋-T碱基对上竞争下来的能力,设计了一种半胱氨酸的检测方法。此方法可以在20～600 nmol/L范围内实现半胱氨酸的定量检测,检出限为14 nmol/L。
The effects of linking loop structure between guanine （ G） repeats on G-quadruplex formation were investigated. The results show that the unfavorable effects of long linking loops on G-quadruplex formation can be overcome by introducing double-stranded structures in linking loop regions. This finding provides a new way for sensor design. The activity of G-quadruplex DNAzyme can be tuned by utilizing target-mediated formation of double-stranded structures in loops. As an example, T-T mismatches are introduced in loops to destroy double-stranded structures. The stabilization of Hg2＋ to T-T mismatches promotes the reformation of double-stranded structures. Correspondingly, the oligonucleotide folds into G-quadruplex, which binds with hemin to form peroxidase-like G-quadruplex DNAzyme. Hg2＋ sensor is designed based on this principle. Using this method, Hg2＋ quantitation is achieved in the concentration range of 10-700 nmol/L, with a detection limit of 8. 7 nmol/L. Cysteine will compete with T bases to bind with Hg2＋, releasing Hg2＋from T-Hg2＋-T base pairs. Thus cysteine can also be quantified with this system in the concentration range of 20-700 nmol/L, with a detection limit of 14 nmol/L.
出处
《分析化学》
SCIE
EI
CAS
CSCD
北大核心
2014年第10期1414-1420,共7页
Chinese Journal of Analytical Chemistry
基金
天津市应用基础与前沿科技研究计划(No.12JCYBJC13300)资助项目
