Abstract
We present a study of the conformational transitions of a helical polymer by using coarse-grained molecular dynamics simulations. With focus on the variation of the dihedral angles, we are able to obtain the monomer-level details of the response of the polymer chain to environmental stimuli (e.g., temperature variation and mechanical forces). Specifically, during the thermo-induced helix–coil transition, all the helices break synchronously. On the contrary, the force-induced helix breaking always starts from the termini, and then the chain behaviors become divergent and temperature dependent. Particularly, at intermediate temperatures, we find that our polymer chain can adopt an asymmetrical half-trans conformation during the stretching procedures, although the chain itself has quite uniform and homogeneous composition.
Highlights
Helical structures, such as the α-helix and the coiled coils, are significant for biomacromolecules, and the changes in their conformations are always connected to certain biological functions.1–4 it is of great interest to study the conformational responses of helical chains to external stimuli, such as the temperature variation and mechanical forces
After the early reports on the helix–coil transitions of homopolypeptides induced by temperature or pH, more and more studies have been done with the single-molecule force spectroscopy via atomic force microscopy (AFM), magnetic tweezers, etc., which allows direct experimental measurement of the mechanical properties of helical polymer chains
In order to better understand the physics behind the experimental observations, molecular dynamics (MD) simulations have been extensively utilized to model the helical chains under tension
Summary
Helical structures, such as the α-helix and the coiled coils, are significant for biomacromolecules, and the changes in their conformations are always connected to certain biological functions. it is of great interest to study the conformational responses of helical chains to external stimuli, such as the temperature variation and mechanical forces. It is of great interest to study the conformational responses of helical chains to external stimuli, such as the temperature variation and mechanical forces. After the early reports on the helix–coil transitions of homopolypeptides induced by temperature or pH, more and more studies have been done with the single-molecule force spectroscopy via atomic force microscopy (AFM), magnetic tweezers, etc., which allows direct experimental measurement of the mechanical properties of helical polymer chains.. We used coarse-grained MD simulations to systematically investigate the conformational transitions of a helical polymer chain with varying temperature and tension.. We employ coarse-grained MD simulation to study the conformational variation of a helical polymer under various temperatures and tension. We find that at certain temperatures, the chain can break its symmetry and adopt asymmetrical conformation during the stretching procedures
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