Aleman-Garcia Miguel Angel, Orbach Ron, Willner Itamar
Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel).
Chemistry. 2014 May 5;20(19):5619-24. doi: 10.1002/chem.201304702. Epub 2014 Mar 28.
Programmed nucleic acid sequences undergo K(+) ion-induced self-assembly into G-quadruplexes and separation of the supramolecular structures by the elimination of K(+) ions by crown ether or cryptand ion-receptors. This process allows the switchable formation and dissociation of the respective G-quadruplexes. The different G-quadruplex structures bind hemin, and the resulting hemin-G-quadruplex structures reveal horseradish peroxidase DNAzyme catalytic activities. The following K(+) ion/receptor switchable systems are described: 1) The K(+) -induced self-assembly of the Mg(2+) -dependent DNAzyme subunits into a catalytic nanostructure using the assembly of G-quadruplexes as bridging unit. 2) The K(+) -induced stabilization of the anti-thrombin G-quadruplex nanostructure that inhibits the hydrolytic functions of thrombin. 3) The K(+) -induced opening of DNA tweezers through the stabilization of G-quadruplexes on the "tweezers' arms" and the release of a strand bridging the tweezers into a closed structure. In all of the systems reversible, switchable, functions are demonstrated. For all systems two different signals are used to follow the switchable functions (fluorescence and the catalytic functions of the derived hemin-G-quadruplex DNAzyme).
程序化核酸序列在钾离子诱导下自组装形成G-四链体，并通过冠醚或穴状配体离子受体去除钾离子来分离超分子结构。这一过程使得相应的G-四链体能够进行可切换的形成和解离。不同的G-四链体结构可结合血红素，所得的血红素-G-四链体结构具有辣根过氧化物酶DNAzyme的催化活性。以下是钾离子/受体可切换系统：1）利用G-四链体的组装作为桥连单元，钾离子诱导镁离子依赖性DNAzyme亚基自组装成催化纳米结构。2）钾离子诱导抗凝血酶G-四链体纳米结构稳定，从而抑制凝血酶水解功能。3）钾离子通过稳定“镊子臂”上的G-四链体诱导DNA镊子打开，并使连接镊子的链释放到封闭结构中。在所有系统中均展示了可逆、可切换的功能。对于所有系统，使用两种不同信号来跟踪可切换功能（荧光以及衍生的血红素-G-四链体DNAzyme催化功能）。
