Date of Original Version
We present the exact solution of a microscopic statistical mechanical model for the transformation of a long polypeptide between an unstructured coil conformation and an α-helix conformation. The polypeptide is assumed to be adsorbed to the interface between a polar and a non-polar environment such as realized by water and the lipid bilayer of a membrane. The interfacial coil-helix transformation is the first stage in the folding process of helical membrane proteins. Depending on the values of model parameters, the conformation changes as a crossover, a discontinuous transition, or a continuous transition with helicity in the role of order parameter. Our model is constructed as a system of statistically interacting quasiparticles that are activated from the helix pseudo-vacuum. The particles represent links between adjacent residues in coil conformation that form a self-avoiding random walk in 2D. Explicit results are presented for helicity, entropy, heat capacity and the average numbers and sizes of both coil and helix segments.
Ganga P Sharma et al J. Stat. Mech. (2015) P01034
Available at: http://dx.doi.org/10.1088/1742-5468/2015/01/P01034