BPCPPDYSOE21 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
BP: Fachverband Biologische Physik
BP 11: Poster A: Single Molecule, Multicellular, Bioimaging, Focus Sessions, etc.
BP 11.7: Poster
Montag, 22. März 2021, 16:30–19:00, BPp
Molecular mechanisms of single alpha helix deformation under tension — Ana Bergues-Pupo1, Reinhard Lipowsky2, and •Ana Vila Verde3 — 1Max Delbrück Center for Molecular Medicine, Berlin, Germany — 2MPI of Colloids and Interfaces, Dept Theory and Bio-Systems, Potsdam, Germany — 3U. Duisburg-Essen, Physics, Duisburg, Germany
Alpha helices (SAHs) that are stable in isolated form have been found in motor proteins, where they connect spatially separated domains. We investigate the force-estension curve and molecular deformation mechanisms of SAHs pulled from the termini, at pull speeds approaching the quasi-static limit, using molecular dynamics simulations with atomistic resolution of the protein and an implicit model for the solvent. SAHs unravel starting from the termini, in a residue-by-residue manner. Contrary to prior simulations of metastable helices, hydrogen bond breaking is not the main event determining the barrier to unfolding of SAHs at all pull speeds we tested. We fit the force-extension curves to the cooperative Sticky Chain model, and extract the distance, xE=0.13 nm, to the transition state, the natural frequency of bond vibration, ν0=0.82 ns−1, and the height, V0=2.9 kcal/mol, of the free energy barrier associated with the deformation of single residues. The results confirm that the Sticky Chain model could be used to analyze experimental force-extension curves of SAHs and other biopolymers.