Nonlinear elasticity of an alpha-helical polypeptide: Monte Carlo studies.
We report on Monte Carlo studies of the elastic properties of the helix-coil wormlike chain model of alpha-helical polypeptides. In this model the secondary structure enters as a scalar (Ising-like) variable that controls the local chain bending modulus. We characterize the nonlinear elastic properties of these molecules including their response to applied tensile forces and bending torques both individually and in combination. We find a pronounced effect of applied torque on the extensional compliance of the molecule and a similar effect of tension on the bending compliance. Finally we speculate that the strongly nonlinear response of alpha-helical polypeptides to combinations of torque and force plays a role in allosteric transitions in proteins.
Chakrabarti
Buddhapriya
B
Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Levine
Alex J
AJ
D004548:Elasticity; D008956:Models, Chemical; D009010:Monte Carlo Method; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary
D010455:Peptides