02183nas a2200325 4500008004500000020001400045245005900059210005800118260000800176300001000184490000600194520131900200653002801519653001301547653002101560653002401581653001301605653002301618653001101641653001601652653002801668653001301696653001001709100001401719700001901733700001601752700002001768700002001788856004901808 2016 Engldsh a2327-912500aModulated orientation-sensitive terahertz spectroscopy0 aModulated orientationsensitive terahertz spectroscopy cJun aA1-A80 v43 a
Intramolecular vibrations of large macromolecules reside in the terahertz range. In particular, protein vibrations are closely spaced in frequency, resulting in a nearly continuous vibrational density of states. This density of vibrations interferes with the identification of specific absorption lines and their subsequent association with specific functional motions. This challenge is compounded with the absorption being dominated by the solvent and local relaxational motions. A strategy for removing the isotropic relaxational loss and isolating specific vibrations is to use aligned samples and polarization-sensitive measurements. Here, we demonstrate a technique to rapidly attain the anisotropic resonant absorbance using terahertz time domain spectroscopy and a spinning sample. The technique, modulated orientation-sensitive terahertz spectroscopy (MOSTS), has a nonzero signal only for anisotropic samples, as demonstrated by a comparison between a silicon wafer and a wire grid polarizer. For sucrose and oxalic acid molecular crystals, the MOSTS response is in agreement with modeled results for the intermolecular vibrations. Further, we demonstrate that, even in the presence of a large relaxational background, MOSTS isolates underlying vibrational resonances. (C) 2016 Chinese Laser Press
10aabsorption-spectroscopy10adynamics10aenzyme catalysis10alow-frequency modes10alysozyme10aneutron-scattering10aOptics10aperspective10apolarization modulation10aproteins10awater1 aSingh, R.1 aGeorge, D., K.1 aBae, C., J.1 aNiessen, K., A.1 aMarkelz, A., G. uhttps://markelz.physics.buffalo.edu/node/24200930nas a2200157 4500008004500000020002200045245008800067210006900155260001900224520041500243653001100658100002000669700001400689700002000703856004900723 2014 Engldsh a978-1-4799-3877-300aMeasurements and Calculations of Protein Intramolecular Vibrations in the THz Range0 aMeasurements and Calculations of Protein Intramolecular Vibratio aNew YorkbIeee3 aWe report the calculations and measurements of intramolecular vibrational modes and their dependence on inhibitor binding in the THz range. We see an increase in anisotropic THz absorption at low frequency with inhibitor binding in both the measurements and calculations. This surprising result suggests an increase in flexibility with binding. We will discuss the possible reasons for this discrepancy.
10acharmm1 aNiessen, K., A.1 aSnell, E.1 aMarkelz, A., G. uhttps://markelz.physics.buffalo.edu/node/24001415nas a2200349 4500008004500000020002200045245004200067210004200109260004900151490000900200520047800209653002300687653001300710653000900723653002300732653002500755653001700780653001200797653002100809653001700830653001400847100001400861700002000875700001900895700001400914700002000928700001300948700002100961700001700982700001700999856004901016 2013 Engldsh a978-0-8194-9392-700aMeasuring phonons in protein crystals0 aMeasuring phonons in protein crystals aBellinghambSpie-Int Soc Optical Engineering0 v86233 aUsing Terahertz near field microscopy we find orientation dependent narrow band absorption features for lysozyme crystals. Here we discuss identification of protein collective modes associated with the observed features. Using normal mode calculations we find good agreement with several of the measured features, suggesting that the modes arise from internal molecular motions and not crystal phonons. Such internal modes have been associated with protein function.
10acorrelated motions10adynamics10amode10amolecular crystals10amolecular vibrations10anormal modes10aphonons10aprotein dynamics10aspectroscopy10aTerahertz1 aAcbas, G.1 aNiessen, K., A.1 aGeorge, D., K.1 aSnell, E.1 aMarkelz, A., G.1 aBetz, M.1 aElezzabi, A., Y.1 aSong, J., J.1 aTsen, K., T. uhttps://markelz.physics.buffalo.edu/node/218