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Globular Structures of a Helix-Coil Copolymer: Self-Consistent Treatment

Christian Nowak·Vakhtang G. Rostiashvili·Thomas A. Vilgis
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Abstract

A self-consistent field theory was developed in the grand-canonical ensemble formulation to study transitions in a helix-coil multiblock globule. Helical and coil parts are treated as stiff rods and self-avoiding walks of variable lengths correspondingly. The resulting field-theory takes, in addition to the conventional Zimm-Bragg (B.H. Zimm, I.K. Bragg, J. Chem. Phys. 31, 526 (1959)) parameters, also three-dimensional interaction terms into account. The appropriate differential equations which determine the self-consistent fields were solved numerically with finite element method. Three different phase states are found: open chain, amorphous globule and nematic liquid-crystalline (LC) globule. The LC-globule formation is driven by the interplay between the hydrophobic helical segments attraction and the anisotropic globule surface energy of an entropic nature. The full phase diagram of the helix-coil copolymer was calculated and thoroughly discussed. The suggested theory shows a clear interplay between secondary and tertiary structures in globular homopolypeptides.

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Christian Nowak, Vakhtang G. Rostiashvili, Thomas A. Vilgis. 2007-01-29. Globular Structures of a Helix-Coil Copolymer: Self-Consistent Treatment. https://doi.org/10.1063/1.2403868

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