  A low-temperature dynamical transition has been reported in several proteins.
We provide the first observation of a `protein-like' dynamical transition in
nonbiological aqueous environments. To this aim we exploit the popular
colloidal system of poly-N-isopropylacrylamide (PNIPAM) microgels, extending
their investigation to unprecedentedly high concentrations. Owing to the
heterogeneous architecture of the microgels, water crystallization is avoided
in concentrated samples, allowing us to monitor atomic dynamics at low
temperatures. By elastic incoherent neutron scattering and molecular dynamics
simulations, we find that a dynamical transition occurs at a temperature
$T_d\sim250$~K, independently from PNIPAM mass fraction. However, the
transition is smeared out on approaching dry conditions. The quantitative
agreement between experiments and simulations provides evidence that the
transition occurs simultaneously for PNIPAM and water dynamics. The similarity
of these results with hydrated protein powders suggests that the dynamical
transition is a generic feature in complex macromolecular systems,
independently from their biological function.
