Relevance of the Speed and Direction of Pulling in Simple Modular Proteins

A theoretical
framework capable of predicting the first unit that
unfolds in pulled modular proteins has been recently introduced, for
“fast enough” pulling velocities. Within this picture,
we investigate the unfolding pathway in a chain of identical units
and predict that the module closest to the pulled end opens first.
Steered molecular dynamics of a simple construct, specifically a chain
composed of two coiled-coil motives, shows that this is indeed the
case. Notwithstanding, the unfolding behavior strongly depends on
the terminus (C or N) from which this homopolyprotein is pulled. Therefore,
anisotropic features are revealed and seem to play an important role
for the observed unfolding pathway.