The topmost layer of the skin forms an elastic barrier to water loss and protects against adsorption of substances from outside the body. Proteins found in this top layer of the skin, keratins, assemble hierarchically into filaments (dimers -> tetramers -> higher-order assemblies -> protofilaments) ¹ . These fibres are thought to play an active role in underpinning the barrier properties, appearance and elasticity of skin. Little is known about how keratin confers these properties - chiefly because it is very demanding to directly obtain the entire atomic-level structure of the smallest protein sub-units (dimer and tetramer). Molecular simulation provides a route to proposing and generating such structural models, for validation against indirect experimental observations. In this work, we use molecular dynamics (MD) simulations to explore the structural and mechanical properties of keratin intermediate filaments at the molecular level. Our results represent the first time that full atomistic structures for keratin sub-units (dimer and tetramer) have been generated, including the head and tail groups of these proteins. These MD simulations of the keratin provide insights into the structural features of the head domain and the specific role interactions in these domains play in holding neighbouring dimers together.