Protein-like folding and free energy landscape of a homopolymer chain

ORAL

Abstract

Many small proteins fold via a first-order ``all-or-none'' transition directly from an expanded coil to a compact native state. We have recently reported an analogous direct coil-to-crystallite transition for a flexible homopolymer [1]. Wang-Landau sampling was used to construct the 1D density of states for square-well chains up to length 256 and a microcanonical analysis shows that for short-range interactions the usual polymer collapse transition is preempted by a direct freezing transition. A 2D configurational probability landscape, built via multi-canonical sampling, reveals a dominant folding pathway and an inherent configurational barrier to folding. Despite the non-unique homopolymer ground state, the thermodynamics of this direct freezing transition are identical to those of two-state protein folding. Homopolymer folding proceeds over a free energy barrier via a transition state folding nucleus, displays a protein-like Chevron plot, and satisfies the van't Hoff two-state criterion.\\[4pt] [1] Phys. Rev. E 79, 050801(R) (2009); J. Chem. Phys. 131, 114907 (2009).

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Authors

  • Mark Taylor

    Dept. of Physics, Hiram College

  • Eric Baer

    Pennsylvania State University, Lincoln University, NHMFL, Brookhaven National Laboratory, University of Wisconsin Oshkosh, The University of Akron, Wayne State University, Physics Department, John Carroll University, Case Western Reserve University, Marietta College, SciPrint.org, High Performance Technologies, Inc., Air Force Institute of Technology, Johannes-Gutenberg-Universit\"at, Mainz, Germany, Martin-Luther-Universit\"at, Halle, Germany, Northwestern University, Youngstown State University, Dept. of Polymer Science, The University of Akron, X-ray Science Division, Argonne National Laboratory, NIST Center for Neutron Research, Electrical Engineering, Youngs. State U., Macromolecular, Case Western Reserve U.

  • Eric Baer

    Pennsylvania State University, Lincoln University, NHMFL, Brookhaven National Laboratory, University of Wisconsin Oshkosh, The University of Akron, Wayne State University, Physics Department, John Carroll University, Case Western Reserve University, Marietta College, SciPrint.org, High Performance Technologies, Inc., Air Force Institute of Technology, Johannes-Gutenberg-Universit\"at, Mainz, Germany, Martin-Luther-Universit\"at, Halle, Germany, Northwestern University, Youngstown State University, Dept. of Polymer Science, The University of Akron, X-ray Science Division, Argonne National Laboratory, NIST Center for Neutron Research, Electrical Engineering, Youngs. State U., Macromolecular, Case Western Reserve U.