Low-temperature solid-state 13C NMR studies of the retinal chromophore in rhodopsin
| Autor: | Johan Lugtenburg, J. M. L. Courtin, Richard A. Mathies, Daniel P. Raleigh, J. A. Pardoen, Valérie Copié, I. Palings, Steven O. Smith, Robert G. Griffin |
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| Rok vydání: | 1987 |
| Předmět: |
Rhodopsin
Magic angle Magnetic Resonance Spectroscopy Protein Conformation Analytical chemistry Tretinoin Biochemistry Mass Spectrometry chemistry.chemical_compound Retinoids Freezing Animals Carbon Isotopes biology Retinal Bacteriorhodopsin Nuclear magnetic resonance spectroscopy Carbon-13 NMR Chromophore Crystallography chemistry Retinaldehyde biology.protein Cattle Retinal Pigments |
| Zdroj: | Biochemistry. 26(6) |
| ISSN: | 0006-2960 |
| Popis: | Magic angle sample spinning (MASS) 13C NMR spectra have been obtained of bovine rhodopsin regenerated with retinal prosthetic groups isotopically enriched with 13C at C-5 and C-14. In order to observe the 13C retinal chromophore resonances, it was necessary to employ low temperatures (-15-----35 degrees C) to restrict rotational diffusion of the protein. The isotropic chemical shift and principal values of the chemical shift tensor of the 13C-5 label indicate that the retinal chromophore is in the twisted 6-s-cis conformation in rhodopsin, in contrast to the planar 6-s-trans conformation found in bacteriorhodopsin. The 13C-14 isotropic shift and shift tensor principal values show that the Schiff base C = N bond is anti. Furthermore, the 13C-14 chemical shift (121.2 ppm) is within the range of values (120-123 ppm) exhibited by protonated (C = N anti) Schiff base model compounds, indicating that the C = N linkage is protonated. Our results are discussed with regard to the mechanism of wavelength regulation in rhodopsin. |
| Databáze: | OpenAIRE |
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