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 Δ Vactiv = (s1* - s1) 0 =+1553 mlmol for the activation reaction, Δ Vdim = (s2 - s1*) 0 =-3810 mlmol for dimerization, and Δ Vprop = (sP - s1) 0 =+361 mlmol for the propagation reaction, where s1 0, s1* 0, s2 0, and sP 0 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.

Original languageEnglish
Article number024908
JournalJournal of Chemical Physics
Issue number2
StatePublished - 2007


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