The coupling of light-induced electron transfer and proton uptake as derived from crystal structures of reaction centres from Rhodopseudomonas viridis modified at the binding site of the secondary quinone, QB.
Lancaster, C.R., Michel, H.(1997) Structure 5: 1339-1359
- PubMed: 9351808 
- DOI: https://doi.org/10.1016/s0969-2126(97)00285-2
- Primary Citation of Related Structures:  
2PRC, 3PRC - PubMed Abstract: 
In a reaction of central importance to the energetics of photosynthetic bacteria, light-induced electron transfer in the reaction centre (RC) is coupled to the uptake of protons from the cytoplasm at the binding site of the secondary quinone (QB). In the original structure of the RC from Rhodopseudomonas viridis (PDB entry code 1PRC), the QB site was poorly defined because in the standard RC crystals it was only approximately 30% occupied with ubiquinone-9 (UQ9). We report here the structural characterization of the QB site by crystallographic refinement of UQ9-depleted RCs and of complexes of the RC either with ubiquinone-2 (UQ2) or the electron-transfer inhibitor stigmatellin in the QB site.
Organizational Affiliation: 
Max-Planck-Institut für Biophysik, Frankfurt am Main, Germany.