Abstract：
We herein report a method for site-selective photo-crosslinking of a DNA duplex. A stilbene pair was introduced into a DNA duplex and a ruthenium complex was conjugated with a triplex-forming oligonucleotide. We demonstrated that [2+2] photocycloaddition of the stilbene pair occurred upon irradiation with visible light when the ruthenium complex was in close proximity due to triplex formation. No reaction occurred when the ruthenium complex was not in proximity to the stilbene pair. The wavelength of visible light used was of lower energy than the wavelength of UV light necessary for direct excitation of stilbene. Quantum chemical calculation indicated that ruthenium complex catalyzed the photocycloaddition via triplet-triplet energy transfer. Site selectivity of this photo-crosslinking system was evaluated using a DNA duplex bearing two stilbene pairs as a substrate; we showed that the site of crosslinking was precisely regulated by the sequence of the oligonucleotide linked to the ruthenium complex. Since this method does not require orthogonal photoresponsive molecules, it will be useful in construction of complex photoresponsive DNA circuits, nanodevices and biological tools.
摘要：
用于光化学的正交光响应系统的开发，生物化学和其他领域已被证明具有挑战性。我们在此报道了一种用于DNA双链体的位点选择性光交联的方法。将二苯乙烯对引入DNA双链体中,并将钌络合物与形成三链体的寡核苷酸缀合。我们证明，当钌络合物由于三链体的形成而紧密靠近时，在可见光照射下发生了二苯乙烯对的[22]光环加成。当钌络合物不接近二苯乙烯对时,不发生反应。所使用的可见光的波长具有比直接激发二苯乙烯所需的UV光的波长更低的能量。量子化学计算表明，钌配合物通过三重态-三重态能量转移催化光环加成。使用带有两个二苯乙烯对的DNA双链体作为底物，评估了该光交联系统的位点选择性；我们表明，交联位点受到与钌络合物连接的寡核苷酸序列的精确调节。由于这种方法不需要正交光响应分子，它将有助于构建复杂的光响应DNA电路，纳米设备和生物工具。
