Proteins, the nano-machines of living systems, are highly dynamicmolecules. The time-scale of functionally relevant motions spans over a very broadrange, from femtoseconds to several seconds. In particular, the pico- to nanosecondsregion is characterized by side-chain and backbone anharmonic fluctuations that areresponsible for many biological tasks like ligand binding, substrate recognition andenzymatic activity. Neutron scattering on hydrated protein powders reveals twomain activations of anharmonic dynamics, characterized by different onset temperatureand amplitude. Here we review our work on synthetic polypeptides, nativeproteins, and single amino acids to identify the physical origin of the two onsets—one involving water-independent local dynamics of methyl groups and, to a minorextent, of aromatic side-chains, and the other one, known as “protein dynamicaltransition”, concerning large scale functional protein fluctuations, most likely inducedby a crossover in the structure and dynamics of hydration water connectedwith the second critical point hypothesis.
|Number of pages||12|
|Journal||IL NUOVO CIMENTO C|
|Publication status||Published - 2016|
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Physics and Astronomy (miscellaneous)