A large geometric distortion in the first photointermediate of rhodopsin, determined by double-quantum solid-state NMR

作者：Concistre Maria^*; Johannessen Ole G; McLean Neville; Bovee Geurts Petra H M; Brown Richard C D; DeGrip Willem J; Levitt Malcolm H

来源：Journal of Biomolecular NMR, 2012, 53(3): 247-256.

DOI：10.1007/s10858-012-9635-4

• Rhodopsin
• Bathorhodopsin
• Magic-angle spinning
• Double-quantum heteronuclear local field experiment
• Double-quantum NMR
• Torsional angle estimation

Double-quantum magic-angle-spinning NMR experiments were performed on 11,12-C-13(2)-retinylidene-rhodopsin under illumination at low temperature, in order to characterize torsional angle changes at the C11-C12 photoisomerization site. The sample was illuminated in the NMR rotor at low temperature (similar to 120 K) in order to trap the primary photointermediate, bathorhodopsin. The NMR data are consistent with a strong torsional twist of the HCCH moiety at the isomerization site. Although the HCCH torsional twist was determined to be at least 40A degrees, it was not possible to quantify it more closely. The presence of a strong twist is in agreement with previous Raman observations. The energetic implications of this geometric distortion are discussed.

• 出版日期2012-7