Protein-Cofactor Interactions in Bacterial Reaction Centers from Rhodobacter sphaeroides R-26: I. Identification of the ENDOR Lines Associated with the Hydrogen Bonds to the Primary Quinone QA⋅−
| Autor: | R.A. Isaacson, Marco Flores, E. C. Abresch, Rafael Calvo, Wolfgang Lubitz, George Feher |
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| Rok vydání: | 2006 |
| Předmět: |
Photosynthetic reaction centre
0303 health sciences Electron nuclear double resonance Semiquinone biology Hydrogen Hydrogen bond Biophysics chemistry.chemical_element 010402 general chemistry Photochemistry biology.organism_classification 01 natural sciences 0104 chemical sciences law.invention Quinone 03 medical and health sciences Rhodobacter sphaeroides chemistry law Electron paramagnetic resonance 030304 developmental biology |
| Zdroj: | Biophysical Journal. 90:3356-3362 |
| ISSN: | 0006-3495 |
| DOI: | 10.1529/biophysj.105.077883 |
| Popis: | Hydrogen bonds are important in determining the structure and function of biomolecules. Of particular interest are hydrogen bonds to quinones, which play an important role in the bioenergetics of respiration and photosynthesis. In this work we investigated the hydrogen bonds to the two carbonyl oxygens of the semiquinone in the well-characterized reaction center from the photosynthetic bacterium Rhodobacter sphaeroides R-26. We used electron paramagnetic resonance and electron nuclear double resonance techniques at 35 GHz at a temperature of 80 K. The goal of this study was to identify and assign sets of 1H-ENDOR lines to protons hydrogen bonded to each of the two oxygens. This was accomplished by preferentially exchanging the hydrogen bond on one of the oxygens with deuterium while concomitantly monitoring the changes in the amplitudes of the 1H-ENDOR lines. The preferential deuteration of one of the oxygens was made possible by the different 1H → 2H exchange times of the protons bonded to the two oxygens. The assignment of the 1H-ENDOR lines sets the stage for the determination of the geometries of the H-bonds by a detailed field selection ENDOR study to be presented in a future article. |
| Databáze: | OpenAIRE |
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