Modelling components of nacre structure in silico: Interactions of a nacre peptide with chitin and an aragonite surface.

The nacre formation process is a fascinating phenomenon involving mineral phase transformations, self-assembly processes, and protein-mineral interactions, resulting in a hierarchical structure that exhibits outstanding mechanical properties. However, this process is only partially known, and many aspects of nacre structure are not well understood, especially at the molecular scale. To understand the interplay between components-aragonite, protein and chitin-of the structure of nacre observed experimentally, we investigate the interactions of a peptide that is part of the protein lustrin A, identified in the nacreous layer of the shell of the abalone Haliotis rufescens, with the (001) crystal surface of aragonite and the chitin molecule. We report the results of atomistic molecular-modelling calculations and molecular-dynamics simulations of the peptide interacting with both the aragonite surface and the chitin polymer. The peptide shows an energetically favourable binding to the aragonite surface. The interaction of the carboxylic groups of the glutamic unit with the crystalline surface is essential to reproduce the characteristic elastomeric properties of this peptide in nacre.