28 February 2002
Elastic proteins: biological roles and mechanical
, Margo Lillie
, Emily Carrington
, Paul Guerette
and Ken Savage
Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
Department of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA
The term ‘elastic protein’ applies to many structural proteins with diverse functions and mechanical
properties so there is room for confusion about its meaning. Elastic implies the property of elasticity, or
the ability to deform reversibly without loss of energy; so elastic proteins should have high resilience.
Another meaning for elastic is ‘stretchy’, or the ability to be deformed to large strains with little force.
Thus, elastic proteins should have low stiffness. The combination of high resilience, large strains and low
stiffness is characteristic of rubber-like proteins (e.g. resilin and elastin) that function in the storage of
elastic-strain energy. Other elastic proteins play very different roles and have very different properties.
Collagen ﬁbres provide exceptional energy storage capacity but are not very stretchy. Mussel byssus
threads and spider dragline silks are also elastic proteins because, in spite of their considerable strength
and stiffness, they are remarkably stretchy. The combination of strength and extensibility, together with
low resilience, gives these materials an impressive resistance to fracture (i.e. toughness), a property that
allows mussels to survive crashing waves and spiders to build exquisite aerial ﬁlters. Given this range of
properties and functions, it is probable that elastic proteins will provide a wealth of chemical structures
and elastic mechanisms that can be exploited in novel structural materials through biotechnology.
elastic proteins; mechanical design; elastin; collagen; byssal ﬁbres; spider silks
The objective of this symposium was to develop an under-
standing of structural design in elastic proteins, to eluci-
date the functional role that these materials play in the
lives of real organisms and to discover whether molecular
mechanisms in these materials could be exploited through
biotechnology. One striking feature of the elastic proteins