We introduce a topology-based nonlinear network model of protein dynamics
with the aim of investigating the interplay of spatial disorder and
nonlinearity. We show that spontaneous localization of energy occurs
generically and is a site-dependent process. Localized modes of nonlinear
origin form spontaneously in the stiffest parts of the structure and display
site-dependent activation energies. Our results provide a straightforward way
for understanding the recently discovered link between protein local stiffness
and enzymatic activity. They strongly suggest that nonlinear phenomena may play
an important role in enzyme function, allowing for energy storage during the
catalytic process.Comment: 4 pages, 5 figures. Minor change