%0 Journal Article %J Biophysical Journal %D 2017 %T Escaping the Water Cage: Protein Intramolecular Vibrations and the Dynamical Transition %A Xu, M. Y. %A Niessen, K. A. %A Deng, Y. T. %A Michki, N. S. %A Markelz, A. G. %K Biophysics %B Biophysical Journal %V 112 %P 318A-318A %8 Feb %@ 0006-3495 %G English %9 Meeting Abstract %M WOS:000402375600574 %R 10.1016/j.bpj.2016.11.1723 %0 Journal Article %J Biophysical Journal %D 2017 %T Orange Carotenoid Protein Picosecond Dynamics Changes with Photo and Chemical Activation %A Deng, Y. T. %A Xu, M. Y. %A Liu, H. J. %A Blankenship, R. E. %A Markelz, A. G. %K Biophysics %B Biophysical Journal %V 112 %P 441A-441A %8 Feb %@ 0006-3495 %G English %9 Meeting Abstract %M WOS:000402375700177 %R 10.1016/j.bpj.2016.11.2355 %0 Conference Proceedings %B 2016 41st International Conference on Infrared, Millimeter, and Terahertz Waves %D 2016 %T Anisotropic Absorption Measurements Reveal Protein Dynamical Transition in Intramolecular Vibrations %A Xu, M. Y. %A Niessen, K. %A Michki, N. %A Deng, Y. T. %A Snell, E. %A Markelz, A. G. %X

Modeling has predicted that intramolecular structural vibrations enables proteins to access functionally important structural change. We show that the vibrational density of states and the isotropic absorption in the terahertz range are only weakly dependent on the protein functional state for several bench marking proteins. At the same time the direction of motions changes dramatically with functional state and with a resulting impact on the anisotropic absorption. Our anisotropic THz microscopy (ATM) measurements confirm this sensitivity. Here we apply the technique to the question of whether the protein dynamical transition (DT) is important to protein function. We find a strong anisotropic resonance at 70 cm(-1) rapidly increases in strength at temperatures above the DT. As these intramolecular vibrations enable protein structure to change conformation, the results suggest function will cease below DT for those proteins that require large scale conformational change.

%B 2016 41st International Conference on Infrared, Millimeter, and Terahertz Waves %S International Conference on Infrared Millimeter and Terahertz Waves %I Ieee %C New York %@ 978-1-4673-8485-8 %G English %M WOS:000391406200009 %R 10.1109/IRMMW-THz.2016.7758347 %0 Conference Proceedings %B 2014 39th International Conference on Infrared, Millimeter, and Terahertz Waves %D 2014 %T Probing the Stability of Fluorescent Proteins by Terahertz Spectroscopy %A Xu, M. Y. %A George, D. K. %A Jimenez, R. %A Markelz, A. G. %K dynamics %X

The higher transmission through tissues of long wavelength light motivates the development of fluorescent proteins with excitation shifted to the red. However red fluorescent proteins (RFPs) are more susceptible to photobleaching than their shorter wavelength counterparts. In particular RFPs are more susceptible to photobleaching [1]. A possible reason for this is a decrease in the structural stability of the beta barrel. Measurements of structural stability include atomic root mean squared displacement <x(2)> measured by the X-ray B-factor and neutron quasi elastic scattering. To date, X-ray measurements of RFP's do not indicate a structural stability change and systematic scattering studies have not been performed. Using THz dielectric response we examine if the picosecond structural flexibility decreases with increasing FP stability.

%B 2014 39th International Conference on Infrared, Millimeter, and Terahertz Waves %S International Conference on Infrared Millimeter and Terahertz Waves %I Ieee %C New York %@ 978-1-4799-3877-3 %G English %M WOS:000378889200449 %R https://doi.org/10.1109/IRMMW-THz.2014.6956442