Amino acid sequence dependence of nanoscale deformation mechanisms in alpha-helical protein filaments

Alpha-helical protein filaments are the key constituent of biological materials such as cells, hair, hoof, and wool, where they assemble to form hierarchical filamentous structures. Here the focus is on the multiscale mechanical properties of this class of protein materials, where a systematic analysis is reported on the competition between protein rupture and interprotein sliding for different molecular geometries and variations in the amino acid sequence. Through this analysis, facilitated by simulations with a coarse-grained mesoscale model of alpha-helical protein domains, key molecular deformation mechanisms are identified in alpha-helical protein filaments. This study specifically focuses on elucidating the nanoscale mechanisms of strain accommodation under variation of structural and chemical parameters. The main finding is that interprotein sliding is a dominating mechanism that persists for a variety of geometries and realistic biologically occurring amino acid sequences.