专题:软物质研究进展

编者按在物理学研究的早期历史上,很多享誉世界的大科学家,如爱因斯坦、朗缪尔、弗洛里等,都对软物质物理的发展做出过开创性贡献.自de Gennes 1991年正式提出"软物质"概念以来,软物质物理学发展更为迅猛,不仅极大地丰富了物理学的研究对象,还对物理学基础研究,尤其是与复杂体系、非平衡现象(如生命现象)密切相关的物理学提出了重大挑战.作为物理学与数学、化学、生物学、工程等学科的重要交叉点,软物质物理的研究无疑对推动多学科的交集协同发展有着极其重

专题:软物质研究进展

编者按在物理学研究的早期历史上,很多享誉世界的大科学家如爱因斯坦、朗缪尔、弗洛里等,都对软物质物理的发展做出过开创性贡献.自de Gennes 1991年正式提出"软物质"概念以来,软物质物理学发展更为迅猛,不仅极大地丰富了物理学的研究对象,还对物理学基础研究,尤其是与复杂体系、非平衡现象(如生命现象)密切相关的物理学提出了重大挑战.作为物理学与数学、化学、生物学、工程等学科的重要交叉点,软物质物理的研究无疑对推动多学科的交集协同发展有着极其重要的作用

Mechano-chemical selections of two competitive unfolding pathways of a single DNA i-motif

The DNA i-motif is a quadruplex structure formed in tandem cytosine-rich sequences in slightly acidic conditions. Besides being considered as a building block of DNA nano-devices, it may also play potential roles in regulating chromosome stability and gene transcriptions. The stability of i-motif is crucial for these functions. In this work, we investigated the mechanical stability of a single i-motif formed in the human telomeric sequence 5′-(CCCTAA)3CCC, which revealed a novel pH and loading rate-dependent bimodal unfolding force distribution. Although the cause of the bimodal unfolding force species is not clear, we proposed a phenomenological model involving a direct unfolding favored at lower loading rate or higher pH value, which is subject to competition with another unfolding pathway through a mechanically stable intermediate state whose nature is yet to be determined. Overall, the unique mechano - chemical responses of i-motif-provide a new perspective to its stability, which may be useful to guide designing new i-motif-based DNA mechanical nano-devices. ? 2014 Chinese Physical Society and IOP Publishing Ltd