Abstract:
: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.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Whitmire SE,Wolpert D,Markelz AG,Hillebrecht JR,Galan J,Birge RRdoi
10.1016/S0006-3495(03)74562-7subject
Has Abstractpub_date
2003-08-01 00:00:00pages
1269-77issue
2eissn
0006-3495issn
1542-0086pii
S0006-3495(03)74562-7journal_volume
85pub_type
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