title: Three-helix-bundle protein in a Ramachandran model.
abstract: We study the thermodynamic behavior of a model protein with 54 amino acids that forms a three-helix bundle in its native state. The model contains three types of amino acids and five to six atoms per amino acid and has the Ramachandran torsional angles phi(i), psi(i) as its degrees of freedom. The force field is based on hydrogen bonds and effective hydrophobicity forces. For a suitable choice of the relative strength of these interactions, we find that the three-helix-bundle protein undergoes an abrupt folding transition from an expanded state to the native state. Also shown is that the corresponding one- and two-helix segments are less stable than the three-helix sequence.
authors.affiliation: Complex Systems Division, Department of Theoretical Physics, Lund University, Sölvegatan 14A, S-223 62 Lund, Sweden. irback@thep.lu.se
authors.forename: A
authors.initials: A
authors.lastname: Irbäck
authors.forename: F
authors.initials: F
authors.lastname: Sjunnesson
authors.forename: S
authors.initials: S
authors.lastname: Wallin
mesh_terms: D008958:Models, Molecular; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D011506:Proteins