02248nas a2200361 4500008004500000020001400045245013500059210006900194260000800263300001400271490000700285520117500292653002401467653001501491653000801506653001001514653001401524653002201538653003301560653001801593653001601611653001701627653002101644653002301665653003601688100002101724700001601745700002001761700002401781700001401805700001801819856004901837 2003 Engldsh a0006-349500aProtein flexibility and conformational state: A comparison of collective vibrational modes of wild-type and D96N bacteriorhodopsin0 aProtein flexibility and conformational state A comparison of col cAug a1269-12770 v853 a
Far infrared ( FIR) spectral measurements of wild-type (WT) and D96N mutant bacteriorhodopsin thin films have been carried out using terahertz time domain spectroscopy as a function of hydration, temperature, and conformational state. The results are compared to calculated spectra generated via normal mode analyses using CHARMM. We find that the FIR absorbance is slowly increasing with frequency and without strong narrow features over the range of 2-60 cm(-1) and up to a resolution of 0.17 cm(-1). The broad absorption shifts in frequency with decreasing temperature as expected with a strongly anharmonic potential and in agreement with neutron inelastic scattering results. Decreasing hydration shifts the absorption to higher frequencies, possibly resulting from decreased coupling mediated by the interior water molecules. Ground-state FIR absorbances have nearly identical frequency dependence, with the mutant having less optical density than the WT. In the M state, the FIR absorbance of the WT increases whereas there is no change for D96N. These results represent the first measurement of FIR absorbance change as a function of conformational state.
10aangstrom resolution10aBiophysics10adna10afilms10afrequency10aharmonic-analysis10ainelastic neutron-scattering10alarge systems10amixed basis10anormal-modes10apurple membranes10astructural-changes10atransform infrared-spectroscopy1 aWhitmire, S., E.1 aWolpert, D.1 aMarkelz, A., G.1 aHillebrecht, J., R.1 aGalan, J.1 aBirge, R., R. uhttps://markelz.physics.buffalo.edu/node/273