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Dynamic Transition from α-Helices to β-Sheets in Polypeptide Coiled-Coil Motifs

Minin, Kirill A., Zhmurov, Artem, Marx, Kenneth A., Purohit, Prashant K., Barsegov, Valeri
Journal of the American Chemical Society 2017 v.139 no.45 pp. 16168-16177
biocompatible materials, chemotaxis, fibrin, myosin, phase transition, phenylalanine, plastic deformation, plasticity, polypeptides, strength (mechanics), topology, vimentin
We carried out dynamic force manipulations in silico on a variety of coiled-coil protein fragments from myosin, chemotaxis receptor, vimentin, fibrin, and phenylalanine zippers that vary in size and topology of their α-helical packing. When stretched along the superhelical axis, all superhelices show elastic, plastic, and inelastic elongation regimes and undergo a dynamic transition from the α-helices to the β-sheets, which marks the onset of plastic deformation. Using the Abeyaratne-Knowles formulation of phase transitions, we developed a new theoretical methodology to model mechanical and kinetic properties of protein coiled-coils under mechanical nonequilibrium conditions and to map out their energy landscapes. The theory was successfully validated by comparing the simulated and theoretical force-strain spectra. We derived the scaling laws for the elastic force and the force for α-to-β transition, which can be used to understand natural proteins’ properties as well as to rationally design novel biomaterials of required mechanical strength with desired balance between stiffness and plasticity.