title: Globular structures of a helix-coil copolymer: self-consistent treatment.
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, [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 segment 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.
authors.affiliation: Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Nowak
authors.forename: V G
authors.initials: VG
authors.lastname: Rostiashvili
authors.forename: T A
authors.initials: TA
authors.lastname: Vilgis