标题： 更热并不意味着更快的熔化RNA发夹结构 显示英文标题

标题： Hotter isn't faster for a melting RNA hairpin

摘要： 我们通过粗粒度RNA发夹模型的大量分子动力学模拟，研究了核酸的变性动力学。 显然与阿伦尼乌斯定律相矛盾，我们的研究结果表明，对于长度超过几个持久长度的分子，RNA发夹的变性时间是温度的非单调函数，在熔点以上的一个最优温度 $T_m$时，变性发生得最快。 这种异常现象源于两种不同的路径：从一端到另一端的“单向”解链，在接近 $T_m$时占优，以及在较高温度下从两端同时开始的“双向”变性。 这两种模式在熔化时间 \textit{vs.}与长度 $L$之间表现出不同的标度规律，并由一个交叉温度 $T_\times$分隔，其中 $(T_\times-T_m) \sim L^{-1}$。 这些结果突显了螺旋结构在RNA/DNA变性非平衡动力学中的重要作用，并揭示了一个几十年老问题中的多个意外发现。 显示英文摘要

摘要： We investigate the denaturation dynamics of nucleic acids through extensive molecular dynamics simulations of a coarse-grained RNA hairpin model. In apparent contradiction with Arrhenius' law, our findings reveal that the denaturation time of RNA hairpins is a non-monotonous function of temperature for molecules longer than few persistence lengths, with an optimal temperature above the melting point, $T_m$, at which denaturation occurs fastest. This anomaly arises from the existence of two distinct pathways: ``unidirectional'' unzipping, progressing from one end to the other and favored near $T_m$, and ``bidirectional'' denaturation, where competing unzipping events initiate from both ends at higher temperatures. The two regimes manifest distinct scaling laws for the melting time \textit{vs.} length, $L$, and are separated by a crossover temperature $T_\times$, with $(T_\times-T_m) \sim L^{-1}$. The results highlight the significant role of the helical structure in the out-of-equilibrium dynamics of RNA/DNA denaturation and unveil multiple surprises in a decades-old problem.