A New Concentration Jump Strategy Reveals the Lifetime of i-Motif at Physiological pH without Force

作者：Jonchhe Sagun; Shrestha Prakash; Ascencio Katia; Mao Hanbin^*

来源：Analytical Chemistry, 2018, 90(5): 3205-3210.

DOI：10.1021/acs.analchem.7604661

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 imotif 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 similar to 3s 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.

• 出版日期2018-3-6