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Exploring the active site structure of a photoreceptor protein by Raman optical activity
Masashi Unno1, Takashi Kikukawa, Masato Kumauchi
1Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University, Saga 840-8502, Japan. unno@cc.saga-u.ac.jp
Abstract:
We have developed a near-infrared excited Raman optical activity (ROA) spectrometer and report the first measurement of near-infrared ROA spectra of a light-driven proton pump, bacteriorhodopsin. Our results demonstrate that a near-infrared excitation enables us to measure the ROA spectra of the chromophore within a protein environment. Furthermore, the ROA spectra of the all-trans, 15-anti and 13-cis, 15-syn isomers differ significantly, indicating a high structural sensitivity of the ROA spectra. We therefore expect that future applications of the near-infrared ROA will allow the experimental elucidation of the active site structures in other proteins as well as reaction intermediates.
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