title: Beta-sheet coil transitions in a simple polypeptide model.
abstract: A simplified model of a polypeptide chain is used to study the dynamics of the beta-sheet-coil transition. Each amino acid residue is treated as a single quasiparticle in an effective potential that approximates the potential of mean force in solution. The model is used to study the equilibrium and dynamic aspects of the sheet-coil transition. Systems studied include ones with both strands free to move (two-strand sheet), and ones with either strand fixed in position (multistrand sheet). The equilibrium properties examined include sheet-coil equilibrium constants and their dependence on chain position. Dynamic properties are investigated by a stochastic simulation of the Brownian motion of the chain in its solvent surroundings. Time histories of the dihedral angles and residue-residue cross-strand distances are used to study the behavior of the sheet structure. Auto- and cross-correlation functions are calculated from the time histories with relaxation times of tens to hundreds of picoseconds. Sheet-coil rate constants of tens of ns-1 were found for the fixed strand cases.
authors.affiliation: Department of Physics, Tufts University, Medford, Massachusetts 02155.
authors.forename: K
authors.initials: K
authors.lastname: Yapa
authors.forename: D L
authors.initials: DL
authors.lastname: Weaver
authors.forename: M
authors.initials: M
authors.lastname: Karplus
mesh_terms: D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D010455:Peptides