Coil-helix transition of polypeptide at water-lipid interface. (27th January 2015)

• Record Type: Journal Article
• Authors: Sharma, Ganga P; Reshetnyak, Yana K; Andreev, Oleg A; Karbach, Michael; Müller, Gerhard
• Is Part Of: Journal of statistical mechanics. (2015:Jan.)
• Publication Date: 2015-01-27
• Subjects: 1 -- 9 -- 10 -- 15; 1/110 -- 9/280 -- 10/180 -- 15/305; Statistical mechanics -- Periodicals; Mechanics -- Statistical methods -- Periodicals; 530.1305
• DOI: 10.1088/1742-5468/2015/01/P01034
• Languages: English
• ISSNs: 1742-5468

Abstract

Abstract: 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.