Structure and binding site of the primary electron acceptor in the reaction center of Chlorobium
| Autor: | Marc Lutz, Bruno Robert, Christine Pourcet, Delphine Albouy, Ute Feiler, Tony A. Mattioli |
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| Rok vydání: | 1994 |
| Předmět: |
Photosynthetic reaction centre
Chlorophyll Chlorophyll a Porphyrins Population Photosynthetic Reaction Center Complex Proteins Light-Harvesting Protein Complexes Chlorobium Photochemistry Spectrum Analysis Raman Biochemistry chemistry.chemical_compound Pigment Magnesium education Bacteriochlorophylls chemistry.chemical_classification education.field_of_study Binding Sites biology Bacteria Chlorophyll A Hydrogen Bonding Electron acceptor biology.organism_classification Acceptor Kinetics chemistry visual_art Chlorin visual_art.visual_art_medium |
| Zdroj: | Biochemistry. 33(24) |
| ISSN: | 0006-2960 |
| Popis: | In isolated, chlorosome-free reaction centers from Chlorobium limicola f thiosulphatophilum, a chlorin pigment exhibits a Qy absorption band at 672 nm (Feiler, U., Nitschke, W., & Michel, H. (1992) Biochemistry 31, 2608-2614). To characterize the chemical nature of this chlorin pigment and its interactions within the reaction-center protein, selective enhancement of its Raman scattering was achieved by resonant excitation within its Soret band. This is the first time that structural studies of this pigment were performed on the native reaction-center protein. The obtained resonance Raman spectra were consistent with a single population of a chlorophyll a(-like) pigment, possessing a vinyl group on ring I, but not with bacteriochlorophyll c or bacteriophaeophytin c. The stretching frequencies of the C9-keto carbonyl of this pigment indicates that it is H-bonded to the reaction-center protein. The strength of this H-bond is very close to those of the keto carbonyls of the primary electron acceptors in purple bacterial reaction centers and D1/D2 particles. Since in membranes of Chlorobiaceae a transient bleaching at 670 nm is due to the primary acceptor in the reaction center (Nuijs, A. M., Vasmel, H., Joppe, H. L. P., Duysens, L. N. M., & Amesz, J. (1985a) Biochim. Biophys. Acta 907, 24-34), we thus conclude that the primary acceptor in Chlorobium reaction centers is the characterized chlorophyll a(-like) pigment.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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