  Glassy, nonexponential relaxations in globular proteins are typically
attributed to conformational behaviors that are missing from intrinsically
disordered proteins. Yet, we show that single molecules of a disordered-protein
construct display two signatures of glassy dynamics, logarithmic relaxations
and a Kovacs memory effect, in response to changes in applied tension. We
attribute this to the presence of multiple independent local structures in the
chain, which we corroborate with a model that correctly predicts the force
dependence of the relaxation. The mechanism established here likely applies to
other disordered proteins.
