INTRODUCTION

The range of application of any science is restricted as much by commerce as by the inherent possibilities of the science and the resulting technology. This is especially true of areas where the immediate profitability is high: typically medicine, sport, and defence. In these areas, the profit motive disappears beneath hopes of survival, on which there is no rational price. Biologically, this is understandable; intellectually, it can be restricting. Equally restricting is the perception of commerce that an improvement of less than 10% is not worth chasing.

Therefore, when trying to see what applications might be suggested by a biomimetic approach to the mechanical properties of proteins, applications in medicine, sport, and defence are the first to be tried. Medicine is seen to be (relatively!) intellectually easy, since the typical working environment will be similar to that in which the protein evolved – temperatures ranging between –20° and +40°C and an aqueous environment. A few proteins (silk and keratin are the obvious examples; collagen as tendon and processed animal skin should be included) are mechanically interesting in the absence of liquid water, and could therefore be considered as paradigms for applications in sport and defence. But elastomeric proteins – such as elastin, titin, and resilin – rely on water not only as a plasticiser, keeping the protein below its glass transition at ambient conditions, but also to allow expression of the hydrophobicity which lies at the heart of the mechanism of long-range (‘rubbery’) elasticity.