Mechanical Properties of Chitin–Protein Interfaces: A Molecular Dynamics Study

Abstract

The mechanical behaviors of chitin, proteins, and their interfaces are important factors in defining the overall mechanical properties of “chitin-based” biological materials, including lobster shells, squid beaks, and spider’s fangs. Additional effects arise from their solvent environments such as water and inorganic ions. In this paper, we explored the molecular-level mechanics of the chitin–protein interface by performing molecular dynamics simulations. Model proteins including α-helices and β-sheets were investigated, showing secondary structure-dependent chitin-binding behaviors through hydrogen bonds (H-bonds). The results indicate that the terminals of proteins anchor them on the chitin substrate through H-bonds and contribute to the interfacial strength. Furthermore, it is shown that the presence of water at the interface reduces its strength by weakening the H-bonds network (by approximately two thirds for the α-helix in our model). The results and conclusion from this simple model for the chitin–protein interface are expected to shed some light on the complete exploration of multiscale mechanics in biological materials with such type of interfaces.