Bacterial Reaction Center Protein Research Articles

Comparative ENDOR study at 34 GHz of the triplet state of the primary donor in bacterial reaction centers of Rb. sphaeroides and Bl. viridis

The primary electron donor (P) in the photosynthetic bacterial reaction center of Rhodobacter sphaeroides and Blastochloris viridis consists of a dimer of bacteriochlorophyll a and b cofactors, respectively. Its photoexcited triplet state in frozen solution has been investigated by time resolved ENDOR spectroscopy at 34 GHz. The observed ENDOR spectra for (3)P865 and (3)P960 are essentially the same, indicating very similar spin density distributions. Exceptions are the ethylidene groups unique to the bacteriochlorophyll b dimer in (3)P960. Strikingly, the observed hyperfine coupling constants of the ethylidene groups are larger than in the monomer, which speaks for an asymmetrically delocalized wave function over both monomer halves in the dimer. The latter observation corroborates previous findings of the spin density in the radical cation states P 865 (•+) (Lendzian et al. in Biochim Biophys Acta 1183:139-160, 1993) and P 960 (•+) (Lendzian et al. in Chem Phys Lett 148:377-385, 1988). As compared to the bacteriochlorophyll monomer, the hyperfine coupling constants of the methyl groups 2(1) and 12(1) are reduced by at least a factor of two, and quantitative analysis of these couplings gives rise to a ratio of approximately 3:1 for the spin density on the halves PL:PM. Our findings are discussed in light of the large difference in photosynthetic activity of the two branches of cofactors present in the bacterial reaction center proteins.

PH Modulates the Quinone Position in the Photosynthetic Reaction Center from Rhodobacter sphaeroides in the Neutral and Charge Separated States

The structure of the photosynthetic reaction-center from Rhodobacter sphaeroides has been determined at four different pH values (6.5, 8.0, 9.0, 10.0) in the neutral and in charge separated states. At pH 8.0, in the neutral state, we obtain a resolution of 1.87 Å, which is the best ever reported for the bacterial reaction center protein. Our crystallographic data confirm the existence of two different binding positions of the secondary quinone (Q B). We observe a new orientation of Q B in its distal position, which shows no ring-flip compared to the orientation in the proximal position. Datasets collected for the different pH values show a pH-dependence of the population of the proximal position. The new orientation of Q B in the distal position and the pH-dependence could be confirmed by continuum electrostatics calculations. Our calculations are in agreement with the experimentally observed proton uptake upon charge separation. The high resolution of our crystallographic data allows us to identify new water molecules and external residues being involved in two previously described hydrogen bond proton channels. These extended proton-transfer pathways, ending at either of the two oxo-groups of Q B in its proximal position, provide additional evidence that ring-flipping is not required for complete protonation of Q B upon reduction.

Fourier transform resonance Raman spectroscopy of bacterial reaction center proteins: The primary electron donor

Fourier transform resonance Raman spectroscopy of bacterial reaction center proteins: The primary electron donor

Electron spin polarization in sequential electron transfer. An example from iron-containing photosynthetic bacterial reaction center proteins

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectron spin polarization in sequential electron transfer. An example from iron-containing photosynthetic bacterial reaction center proteinsSeth W. Snyder, Andrea L. Morris, Stephen R. Bondeson, James R. Norris, and Marion C. ThurnauerCite this: J. Am. Chem. Soc. 1993, 115, 9, 3774–3775Publication Date (Print):May 1, 1993Publication History Published online1 May 2002Published inissue 1 May 1993https://doi.org/10.1021/ja00062a053RIGHTS & PERMISSIONSArticle Views64Altmetric-Citations18LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (293 KB) Get e-Alerts Get e-Alerts