Ostrovsky B, Bar-Yam Y
Electrical, Computer and Systems Engineering Department, College of Engineering, Boston University, Massachusetts 02215, USA.
Biophys J. 1995 May;68(5):1694-8. doi: 10.1016/S0006-3495(95)80347-4.
To investigate the polymer coil-to-globule transition we performed simulations for the kinetics of homopolymer and heteropolymer collapse. Our stimulations made use of abstract models of long flexible polymers to obtain extensive statistical sampling. For a variety of these models, the simulations suggest that collapse of long polymers is dominated by diffusion of the polymer ends, which accrete monomers and small aggregates. The growth of the end aggregate was found to be nearly linear in time for homopolymers and largely unaffected by variations in microstructure. In contrast, for heteropolymers the presence of non-aggregating (hydrophilic) monomers dramatically slows and alters the growth of the end mass. In models simulated, the end mass grows roughly as the cube root of time, but still dominates aggregation along the contour. In a model where only pairwise bonding is allowed, the collapse is uniform since more flexible end motion does not result in continued end accretion. The possible significance of our results for biopolymer kinetics is discussed.
为了研究聚合物的线圈到球体转变，我们对均聚物和杂聚物塌陷的动力学进行了模拟。我们的模拟利用了长柔性聚合物的抽象模型来获得广泛的统计采样。对于这些模型中的多种情况，模拟表明长聚合物的塌陷主要由聚合物末端的扩散主导，聚合物末端会吸附单体和小聚集体。对于均聚物，末端聚集体的生长在时间上几乎呈线性，并且在很大程度上不受微观结构变化的影响。相比之下，对于杂聚物，非聚集（亲水）单体的存在会显著减慢并改变末端质量的增长。在模拟模型中，末端质量大致随时间的立方根增长，但仍主导着沿轮廓的聚集。在一个只允许成对键合的模型中，塌陷是均匀的，因为更灵活的末端运动不会导致末端持续吸附。我们讨论了这些结果对生物聚合物动力学可能具有的意义。
