Carbon-13 magic angle spinning NMR evidence for a 15, 15'-cis configuration of the spheroidene in the Rhodobacter sphaeroides photosynthetic reaction center
Autor: | Arnold J. Hoff, de Groot Hj, R. Gebhard, Carol A. Violette, Harry A. Frank, van der Hoef I, J. Lugtenburg |
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Jazyk: | angličtina |
Rok vydání: | 1992 |
Předmět: |
Photosynthetic reaction centre
chemistry.chemical_classification Carbon Isotopes Magnetic Resonance Spectroscopy Magic angle biology Double bond Chemistry Photosynthetic Reaction Center Complex Proteins Molecular Conformation Rhodobacter sphaeroides Carbon-13 NMR biology.organism_classification Photochemistry Carotenoids Biochemistry Crystallography Magic angle spinning Isomerization Cis–trans isomerism |
Zdroj: | Biochemistry, 31(49), 12446-12450 |
Popis: | The photosynthetic reaction center of Rhodobacter sphaeroides 2.4.1 contains one carotenoid that protects the protein complex against photodestruction. The structure around the central (15,15') double bond of the bound spheroidene carotenoid was investigated with low-temperature magic angle spinning 13C NMR, which allows an in situ characterization of the configuration of the central double bond in the carotenoid. Carotenoidless reaction centers of R. sphaeroides R26 were reconstituted with spheroidene specifically labeled at the C-14' or C-15' position, and the signals from the labels were separated from the natural abundance background using 13C MAS NMR difference spectroscopy. The resonances shift 5.2 and 3.8 ppm upfield upon incorporation in the protein complex, similar to the 5.6 and 4.4 ppm upfield shift occurring in the model compound beta-carotene upon trans to 15,15'-cis isomerization. Hence the MAS NMR favors a cis configuration, as opposed to the trans configuration deduced from X-ray data. |
Databáze: | OpenAIRE |
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