Structure and Mechanical Properties of Human Trichocyte Keratin Intermediate Filament Protein

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 alpha-helical structures under loading, suggesting that disulfide bonds play a significant role in achieving the characteristic mechanical properties of trichocyte, alpha-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 poisibility. to study the mechanical properties of hair fibrils and Other fibers from a bottom up perspective.