@article {545, title = {Functional-State Dependence of Picosecond Protein Dynamics}, journal = {J. Phys. Chem. B}, volume = {125}, year = {2021}, pages = {11134-11140}, chapter = {11134}, abstract = {

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{\textendash}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.

}, doi = {10.1021/acs.jpcb.1c05018}, author = {George, D. K. and Chen, J. Y. and He, Yunfen and Knab, J. R. and Markelz, A. G.} } @article {264, title = {FAR-INFRARED SATURATION SPECTROSCOPY OF A SINGLE SQUARE-WELL}, journal = {Semiconductor Science and Technology}, volume = {9}, number = {5}, year = {1994}, note = {Sherwin, Mark S/Q-4762-2017
Sherwin, Mark S/0000-0002-3869-1893; Markelz, Andrea/0000-0003-0443-4319
S
8th International Conference on Hot Carriers in Semiconductors
Aug 16-20, 1993
Oxford univ, oxford, england
Sci \& engn res council; royal soc; brit council; oxford univ
31}, month = {May}, pages = {627-629}, abstract = {

We 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.

}, isbn = {0268-1242}, doi = {10.1088/0268-1242/9/5S/061}, author = {Craig, K. and Felix, C. L. and Heyman, J. N. and Markelz, A. G. and Sherwin, M. S. and Campman, K. L. and Hopkins, P. F. and Gossard, A. C.} }