Sebastiani Federico, Pietrini Alberto, Longo Marialucia, Comez Lucia, Petrillo Caterina, Sacchetti Francesco, Paciaroni Alessandro
Dipartimento di Fisica, Università degli Studi di Perugia , Via Pascoli, I-06123 Perugia, Italy.
J Phys Chem B. 2014 Apr 10;118(14):3785-92. doi: 10.1021/jp411096d. Epub 2014 Mar 26.
The melting transition of A- and B-DNA has been investigated by wide-angle X-ray diffraction. A significant crystalline phase is present in both the systems, even if the fibers have not been artificially aligned. The behavior of the intramolecular Bragg peaks of both A- and B-DNA as a function of the temperature clearly reveals the unfolding structural transition of the double helix. This transition occurs at the same temperature as the melting of the crystalline phase. The trends of the intramolecular correlations and the index of crystallinity are nicely described by the Peyrard-Bishop-Dauxois model for DNA melting. A description of the processes taking place at a microscopic level, i.e., double-helix deformation, crystalline dilation, and collapse, on approaching and during thermal melting is proposed.
通过广角X射线衍射研究了A-DNA和B-DNA的熔融转变。即使纤维未经过人工排列，两个体系中均存在显著的晶相。A-DNA和B-DNA的分子内布拉格峰随温度的变化行为清楚地揭示了双螺旋的解折叠结构转变。该转变发生在与晶相熔化相同的温度下。DNA熔化的佩拉尔-毕晓普-多克索模型很好地描述了分子内相关性和结晶度指数的变化趋势。本文提出了在接近热熔化和热熔化过程中微观层面发生的过程的描述，即双螺旋变形、晶体膨胀和塌陷。
