Energy transfer and trapping in photosynthesis

In a world of increasing atmospheric CO2, there is intensified interest in the ecophysiology of photosynthesis and more attention is being given to other aspects of carbon exchange and storage in natural ecosystems. For example, how much will the photosynthesis of terrestrial and aquatic vegetation change as global CO2 increases? Are there major ecosystems, such as the boreal forests, which may become important sinks of CO2 and slow down the effects of anthropogenic CO2 emissions on climate? This volume reviews the progress which has been made in understanding photosynthesis in the past few decades at several levels of integration, from the molecular level to canopy, ecosystem and global scales.

Ecophysiology of Photosynthesis

Electron Transfer Past and Future (R Marcus) Electron Transfer Reactions in Solution: A Historical Perspective (N Sutin) Electron Transfer--From Isolated Molecules to Biomolecules (M Bixon & J Jortner) Charge Transfer in Bichromophoric Molecules in the Gas Phase (D Levy) Long--Range Charge Separation in Solvent--Free Donor--Bridge--Acceptor Systems (B Wegewijs & J Verhoeven) Electron Transfer and Charge Separation in Clusters (C Dessent, et al) Control of Electron Transfer Kinetics: Models for Medium Reorganization and Donor--Acceptor Coupling (M Newton) Theories of Structure--Function Relationships for Bridge--Mediated Electron Transfer Reactions (S Skourtis & D Beratan) Fluctuations and Coherence in Long--Range and Multicenter Electron Transfer (G Iversen, et al) Lanczos Algorithm for Electron Transfer Rates in Solvents with Complex Spectral Densities (A Okada, et al) Spectroscopic Determination of Electron Transfer Barriers and Rate Constants (K Omberg, et al) Photoinduced Electron Transfer Within Donor--Spacer--Acceptor Molecular Assemblies Studied by Time--Resolved Microwave Conductivity (J Warman, et al) From Close Contact to Long--Range Intramolecular Electron Transfer (J Verhoeven) Photoinduced Electron Transfers Through sigma Bonds in Solution (N--C Yang, et al) Indexes

Electron transfer : from isolated molecules to biomolecules

https://www.cell.com/article/S0969212694000948/pdf

Structure of the photosynthetic reaction centre from Rhodobacter sphaeroides at 2.65 A resolution: cofactors and protein-cofactor interactions

T.J. DiMagno and JR. Volume 2: P.L. Duttonn, C.C. Moser, J.M. Keske, K. Warncke, and R.S. Farid, Electron-Transfer Mechanisms in Reaction Centers: Engineering Guidelines. A. Warshel and W.W. Parson, Simulations of Electron Transfer in Bacterial Reaction Centres. C. Kirmaier and D. Holten, Electron Transfer and Charge Recombination Reactions in Wild-type and Mutant Bacterial Reaction Centres. W. Zinth and W. Kaiser, Time Resolved Spectroscopy of the Primary Electron Transfer in Reaction Centers of Rb. sphaeroides and Rps. viridis. V.A. Shuvalov, Tune and Frequency Domain Study of Different Electron Transfer Processes in Bacterial Reaction Centres.Morris, Electron Transfer in Photosynthetic Bacteria. G.J. Small and R. Jankowiak Spectral Hole Bunting: A Window on Excited State Electronic Structure, Heterogeneity, Electron-Phonon Coupling and Transport Dynamics of Photosynthetic Units. S.G. Boxer, Photosynthetic Reaction Centre Spectroscopy and Electron Transfer Dynamics in Applied Electric Fields. H.A. Frank Carotenoids in Photosynthetic Bacterial Reaction Centers: Structure, Spectroscopy, and Photochemistry. W. Maentele, Infrared Vibrational Spectroscopy of the Photosynthetic Reaction Center. M.C. Thurnauer and S. Snyder, Electron Spin Polarization in Photosynthetic Reaction Centres. A.J. Hoff, Magnetic Resonance of Bacterial Photosynthetic Reaction Centres. H. Levanon and M.K. Bowman, Tune-domain EPR Spectroscopy of Energy and Electron Transfer. D. Gust and T.A. Moore, Multi-step Electron and Energy Transfer in Artificial Photosynthesis. M.R. Wasielewski, Modelling Primary Electron Transfer in Photosynthesis using Supra-molecular Structures. J. Fajer and K.M. Barkigia, Models of Photosynthetic Chromophores, Molecular Structures of Chlorins, and Bacteriochlorins. J. Deisenhofer and H. Michel, The Three-Dimensional Structure of the Reaction Centre from Rhodopseudomonas viridis.

The Photosynthetic Reaction Center

The primary electron transfer in reaction centers of Rhodobacter sphaeroides is studied by subpicosecond absorption spectroscopy with polarized light in the spectral range of 920-1040 nm. Here the bacteriochlorophyll anion radical has an absorption band while the other pigments of the reaction center have vanishing ground-state absorption. The transient absorption data exhibit a pronounced 0.9-ps kinetic component which shows a strong dichroism. Evaluation of the data yields an angle between the transition moments of the special pair and the species related with the 0.9-ps kinetic component of 26 +/- 8 degrees. This angle compares favorably with the value of 29 degrees expected for the reduced accessory bacteriochlorophyll. Extensive transient absorbance data are fully consistent with a stepwise electron transfer via the accessory bacteriochlorophyll.

The accessory bacteriochlorophyll: A real electron carrier in primary photosynthesis

Femtosecond spectroscopy was used in combination with site-directed mutagenesis to study the
influence of tyrosine M210 (YM210) on the primary electron transfer in the reaction center of Rhodobacter
sphaeroides. The exchange of YM210 to phenylalanine caused the time constant of primary electron transfer
to increase from 3.5 f 0.4 ps to 16 f 6 ps while the exchange to leucine increased the time constant even
more to 22 f 8 ps. The results suggest that tyrosine M210 is important for the fast rate of the primary
electron transfer.

/pdf/role-of-tyrosine-m210-in-the-initial-charge-separation-of-2h7rksejl7.pdf

Role of tyrosine M210 in the initial charge separation of reaction centers of Rhodobacter sphaeroides

Temperature dependence of the primary electron transfer in photosynthetic reaction centers from Rhodobacter sphaeroides

Stable subpicosecond infrared pulses in the spectral region of 4.5–11.5 μm are generated by difference-frequency mixing in AgGaS2. The system uses femtosecond pulses from a Ti:sapphire regenerative amplifier and from a tunable traveling-wave dye laser. The infrared pulses have a duration of 400 fs, an energy of more than 10 nJ, and a repetition rate of 1 kHz.

https://epub.ub.uni-muenchen.de/3777/1/87.pdf

Generation of tunable subpicosecond light pulses in the midinfrared between 4.5 and 11.5 μm

M subunit Trp252 is the only amino acid residue which is located between the bacteriopheophytin HA and the quinone QA in the photosynthetic reaction centre of Rhodobacter sphaeroides. Oligodeoxynucleotide-directed mutagenesis was employed to elucidate the influence of this aromatic amino acid on the electron transfer between these two chromophores. For this, M subunit Trp252 was changed to tyrosine or phenylalanine, and Thr222, which presumably forms a hydrogen bridge to the indole ring of M subunit Trp252, to valine. In all three mutated reaction centres, the electron-accepting ubiquinone QA is less firmly bound to its binding site than in the wild-type protein. The electron transfer from the reduced bacteriopheophytin HA− to QA proceeds in the wild-type and in the mutant ThrM222Val within 220 ps. However, in the mutants TrpM252Tyr and TrpM252Phe the time constants are 600 ps and 900 ps, respectively. This indicates that M subunit Trp252 participates in the binding of QA and reduction of this quinone.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1432-1033.1994.tb18987.x

Christoph Lauterwasser

Papers

The accessory bacteriochlorophyll: A real electron carrier in primary photosynthesis

Role of tyrosine M210 in the initial charge separation of reaction centers of Rhodobacter sphaeroides

Temperature dependence of the primary electron transfer in photosynthetic reaction centers from Rhodobacter sphaeroides

Generation of tunable subpicosecond light pulses in the midinfrared between 4.5 and 11.5 μm

Influence of M subunit Thr222 and Trp252 on quinone binding and electron transfer in Rhodobacter sphaeroides reaction centres