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/54501316nas a2200229 4500008004100000020001400041245006500055210006300120260000800183300001200191490000600203520067700209100001400886700001800900700001900918700002000937700002000957700002000977700002000997700002001017856004901037 1994 eng d a0268-124200aFAR-INFRARED SATURATION SPECTROSCOPY OF A SINGLE SQUARE-WELL0 aFARINFRARED SATURATION SPECTROSCOPY OF A SINGLE SQUAREWELL cMay a627-6290 v93 aWe have performed saturation spectroscopy measurements of the lowest intersubband transition in a single 400 angstrom GaAs/Al0.3Ga0.7As modulation-doped square quantum well. We couple intense tunable far-infrared radiation from the Santa Barbara free electron laser into our sample using an edge-coupling technique and measure absorption as a function of frequency and intensity. Saturation and frequency shifts in the absorption line are clearly observed. We attribute the frequency shifts to reductions in the many-body depolarization shift. From our preliminary measurements, we estimate the intersubband relaxation time to be 600 ps to within a factor of three.
1 aCraig, K.1 aFelix, C., L.1 aHeyman, J., N.1 aMarkelz, A., G.1 aSherwin, M., S.1 aCampman, K., L.1 aHopkins, P., F.1 aGossard, A., C. uhttps://markelz.physics.buffalo.edu/node/264