title: Structure and mechanical properties of human trichocyte keratin intermediate filament protein.
abstract: Keratin is a protein in the intermediate filament family and the key component of hair, nail, and skin. Here we report a bottom-up atomistic model of the keratin dimer, using the complete human keratin type k35 and k85 amino acid sequence. A detailed analysis of geometric and mechanical properties through full-atomistic simulation with validation against experimental results is presented. We introduce disulfide cross-links in a keratin tetramer and compare the mechanical behavior of the disulfide bonded systems with a system without disulfide bonds. Disulfide bond results in a higher strength (20% increase) and toughness (49% increase), but the system loses α-helical structures under loading, suggesting that disulfide bonds play a significant role in achieving the characteristic mechanical properties of trichocyte α-keratin. Our study provides general insight into the effect of disulfide cross-link on mechanical properties. Moreover, the availability of an atomistic model of this protein opens the possibility to study the mechanical properties of hair fibrils and other fibers from a bottom-up perspective.
authors.affiliation: Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 1-235A,B, Cambridge, MA 02139, USA.
authors.forename: Chia-Ching
authors.initials: CC
authors.lastname: Chou
authors.forename: Markus J
authors.initials: MJ
authors.lastname: Buehler
mesh_terms: D000595:Amino Acid Sequence; D004220:Disulfides / Q000737:chemistry; D006197:Hair / Q000737:chemistry; D006801:Humans; D053564:Keratins, Hair-Specific / Q000737:chemistry*; D055503:Protein Multimerization; D017433:Protein Structure, Secondary
chemical_list: D004220:Disulfides; D053564:Keratins, Hair-Specific