Artyomov Maxim N, Freed Karl F
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
J Chem Phys. 2007 Jan 14;126(2):024908. doi: 10.1063/1.2409928.
An extended Flory-Huggins-type equilibrium polymerization theory for compressible systems is used to describe experimental data for the unusual pressure and temperature dependence of the equilibrium polymerization of G-actin to F-actin. The calculations provide rich insights into the reaction mechanism and the thermodynamics of actin polymerization at the molecular level. Volume changes associated with individual steps of the mechanism are calculated to be DeltaVactiv=(s1*-s1)upsilon0=+1553 mlmol for the activation reaction, DeltaVdim=(s2-s1*)upsilon0=-3810 mlmol for dimerization, and DeltaVprop=(sP-s1)upsilon0=+361 mlmol for the propagation reaction, where s1upsilon0, s1*upsilon0, s2upsilon0, and sPupsilon0 are the monomer volumes in the G-actin monomer, the activated G-action, the dimer, and higher polymers, respectively. Comparison with experimental measurements is made, and discrepancies are discussed.
一种用于可压缩体系的扩展弗洛里-哈金斯型平衡聚合理论被用来描述G-肌动蛋白向F-肌动蛋白平衡聚合过程中不同寻常的压力和温度依赖性的实验数据。这些计算在分子水平上为肌动蛋白聚合的反应机理和热力学提供了丰富的见解。与该机理各个步骤相关的体积变化经计算得出，活化反应的ΔVactiv =(s1*-s1)υ0 = +1553 ml/mol，二聚反应的ΔVdim =(s2 - s1*)υ0 = -3810 ml/mol，链增长反应的ΔVprop =(sP - s1)υ0 = +361 ml/mol，其中s1υ0、s1*υ0、s2υ0和sPυ0分别是G-肌动蛋白单体、活化的G-肌动蛋白、二聚体和更高聚合物中的单体体积。文中进行了与实验测量值的比较，并讨论了差异。
