Biochemistry 2010, 49, 3343–3350 3343 DOI: 10.1021/bi100184k
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Low-Temperature FTIR Study of Gloeobacter Rhodopsin: Presence of Strongly Hydrogen-Bonded Water and Long-Range Structural Protein Perturbation upon Retinal Photoisomerization Kyohei Hashimoto,‡ Ah Reum Choi,§ Yuji Furutani,‡, Kwang-Hwan Jung,§ and Hideki Kandori*,‡ Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan, and § Department of Life Science and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Seoul 121-742, Korea. Present address: Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan. )
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Received February 5, 2010; Revised Manuscript Received March 13, 2010 ABSTRACT:
Gloeobacter rhodopsin (GR) is a light-driven proton-pump protein similar to bacteriorhodopsin (BR), found in Gloeobacter violaceus PCC 7421, a primitive cyanobacterium. In this paper, structural changes of GR following retinal photoisomerization are studied by means of low-temperature Fourier-transform infrared (FTIR) spectroscopy. The initial motivation was to test our hypothesis that proton-pumping rhodopsins possess strongly hydrogen-bonded water molecules in the active center. Water O-D stretching vibrations at
