Physical Chemistry, Department of Chemistry, Lund University, Box 124, SE-221 00 Lund, Sweden.
J Phys Chem B. 2011 Oct 6;115(39):11448-54. doi: 10.1021/jp2019395. Epub 2011 Sep 8.
A new two-state polymer folding model is proposed, in which the folding of a stiff helical polymer is enabled by allowing for short sequences of coils connecting shorter and separated helices. The folding is driven by short-range attraction energy among stacked helices and is opposed by the free-energy cost of forming coils from helical monomers. Principal outcomes of the model are equilibrium distribution of the number of helices and their length in helical polymers. The proposed model is applied to α-helical polyalanine. The distribution of the number of α-helices as a function of number of alanine residues is fitted to the corresponding result from molecular dynamics simulation employing an all-atom potential model with very good agreement. The influence and significance of the fitting parameters and possible use of the two-state folding model are discussed.
提出了一种新的两态聚合物折叠模型，其中通过允许连接较短和分离的螺旋的短线圈序列，使刚性螺旋聚合物能够折叠。折叠由堆叠螺旋之间的短程吸引能驱动，而由从螺旋单体形成线圈的自由能成本反对。该模型的主要结果是螺旋聚合物中螺旋的数量及其长度的平衡分布。将所提出的模型应用于α-螺旋聚丙氨酸。通过与使用全原子势能模型的分子动力学模拟的对应结果非常吻合，拟合了α-螺旋数作为丙氨酸残基数的函数的分布。讨论了拟合参数的影响和意义以及两态折叠模型的可能用途。
