Molecular Design of the α-keratin Composite: Insights from a Matrix-free Model, Hagfish Slime Threads

Document Type


Publication Date



We performed mechanical tests on a matrix-free keratin model—hagfish slime threads—to test the hypothesis that intermediate filaments (IFs) in hydrated hard α-keratins are maintained in a partly dehydrated state. This hypothesis predicts that dry IFs should possess mechanical properties similar to the properties of hydrated hard α-keratins, and should swell more than hard α-keratins in water. Mechanical and swelling measurements of hagfish threads were consistent with both of these predictions, suggesting that an elastomeric keratin matrix resists IF swelling and keeps IF stiffness and yield stress high. The elastomeric nature of the matrix is indirectly supported by the inability of matrix-free IFs (i.e. slime threads) to recover from post-yield deformation. We propose a general conceptual model of the structural mechanics of IF-based materials that predicts the effects of hydration and cross-linking on stiffness, yield stress and extensibility


This article was originally published in Proceedings of the Royal Society B, volume 271, in 2004. DOI: 10.1098/rspb.2003.2591


Royal Society