A New Concentration Jump Strategy Reveals the Lifetime of i-Motif at Physiological pH without Force
A New Concentration Jump Strategy Reveals the Lifetime of i-Motif at Physiological pH without Force
复制标题
一种新的浓度跳跃策略揭示了 i-Motif 在生理 pH 值（无外力）下的寿命
DOI：
10.1021/acs.analchem.7b04661
复制
发表时间：
2018
影响因子：
7.4
通讯作者：
Mao, Hanbin
中科院分区：
文献类型：
--
作者：
Jonchhe, Sagun;Shrestha, Prakash;Ascencio, Katia;Mao, Hanbin
动力学测量的浓度跃变仍然是单分子技术的挑战，与系综平均方法相比，单分子技术已经证明了上级信噪比水平。目前，所有的浓度跳跃都使用混合策略。在这里，我们报告了一个简单的和完全不同的跳跃策略，通过在80毫秒内两个并排层流之间快速运输分子。这使我们能够在生理pH下测量生物活性DNA i基序结构的寿命，而无需强制。我们将人类端粒的i基序内的DNA发夹为基础的机械报告。由于发夹的折叠或未折叠状态与i基序的折叠或未折叠状态相关，因此通过记录发夹转换，发现DNA i基序在中性pH值（不受力）下的半衰期为0.3s。这样的寿命足以使i基序与蛋白质相互作用以调节细胞过程。我们预计这种浓度跳跃提供了一个通用的平台，研究单分子动力学。
Concentration jumps for kinetics measurement remain a challenge for single-molecule techniques, which have demonstrated superior signal-to-noise levels compared to ensemble average approaches. Currently, all concentration jumps use mixing strategies. Here, we report a simple and drastically different jump strategy by rapid transportation of molecules between two side-by-side laminar streams in 80 ms. This allowed us to measure the lifetime of bioactive DNA i-motif structures at physiological pH without force. We placed a human telomeric i-motif inside a DNA hairpin-based mechanical reporter. Since the folded or unfolded state of the hairpin correlates with that of the i-motif, by recording hairpin transitions, a half-life of ∼3 s was found for the DNA i-motif at neutral pH without force. Such a lifetime is sufficient for i-motif to interact with proteins to modulate cellular processes. We anticipate this concentration jump offers a generic platform to investigate single-molecule kinetics.