Deng Minggang, Zhang Dan, Zhou Yangyang, Zhou Xiang
College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Hubei, Wuhan, 430072, PR of China.
J Am Chem Soc. 2008 Oct 1;130(39):13095-102. doi: 10.1021/ja803507d. Epub 2008 Sep 3.
G-quadruplex containing peroxidase DNAzyme is a complex of hemin and a single-stranded guanine-rich DNA (hemin-binding DNA aptamer), which is used as an attractive catalytic label for biosensing recently. Therein, the hemin-binding DNA aptamer contains four GGG repeats and can fold into a G-quadruplex structure. In this paper, we have developed a new split mode to divide the hemin-binding DNA aptamer into two parts: one possesses three GGG repeats, and another part possesses one GGG repeat, namely, the 3:1 split mode. The combination of G-quadruplex and hemin binding could be used as a sensitive probe for the identification of single nucleotide polymorphisms by giving a color signal, visible to the naked eye at room temperature. The G-quadruplex containing peroxidase DNAzyme utilizes the 3:1 split mode and can be directly used for the identification of SNPs with a detection limit in the nM range when the matching length of the probe is short enough. When the matching length of the probe is relatively long, another method adding competition sequences to the probe could also operate effectively for the identification of SNPs. The results also suggested that we could detect the signal when the mutation sample was only 5% in the total target DNA with a competition strategy.
含过氧化物酶的G-四链体DNAzyme是血红素与富含鸟嘌呤的单链DNA（血红素结合DNA适体）的复合物，最近被用作生物传感中一种有吸引力的催化标记物。其中，血红素结合DNA适体包含四个GGG重复序列，可折叠成G-四链体结构。在本文中，我们开发了一种新的拆分模式，将血红素结合DNA适体分为两部分：一部分含有三个GGG重复序列，另一部分含有一个GGG重复序列，即3:1拆分模式。G-四链体与血红素结合的组合可作为一种灵敏的探针，通过在室温下肉眼可见的颜色信号来鉴定单核苷酸多态性。含过氧化物酶的G-四链体DNAzyme利用3:1拆分模式，当探针的匹配长度足够短时，可直接用于鉴定单核苷酸多态性，检测限在纳摩尔范围内。当探针的匹配长度相对较长时，另一种向探针中添加竞争序列的方法也可有效用于鉴定单核苷酸多态性。结果还表明，采用竞争策略时，当突变样本在总目标DNA中仅占5%时，我们就能检测到信号。
