01555nas a2200169 4500008004100000245006300041210006200104300001600166490000800182520105800190100001901248700001701267700001501284700001701299700002001316856004901336 2021 eng d00aFunctional-State Dependence of Picosecond Protein Dynamics0 aFunctionalState Dependence of Picosecond Protein Dynamics a11134-111400 v1253 a

We examine temperature-dependent picosecond dynamics of two benchmarking proteins lysozyme and cytochrome c using temperature-dependent terahertz permittivity measurements. We find that a double Arrhenius temperature dependence with activation energies E1 ∼ 0.1 kJ/mol and E2 ∼ 10 kJ/mol fits the folded and ligand-free state response. The higher activation energy is consistent with the so-called protein dynamical transition associated with beta relaxations at the solvent–protein interface. The lower activation energy is consistent with correlated structural motions. When the structure is removed by denaturing, the lower-activation-energy process is no longer present. Additionally, the lower-activation-energy process is diminished with ligand binding but not for changes in the internal oxidation state. We suggest that the lower-energy activation process is associated with collective structural motions that are no longer accessible with denaturing or binding.

1 aGeorge, D., K.1 aChen, J., Y.1 aHe, Yunfen1 aKnab, J., R.1 aMarkelz, A., G. uhttps://markelz.physics.buffalo.edu/node/545