Primary Charge Separation Between P700* and the Primary Electron Acceptor Complex A-A0: A Comparison with Bacterial Reaction Centers
The mechanism of charge separation and the stabilization of separated charges in photosystem I (PS I) is considered in comparison with reaction centers (RCs) in bacteria. The analysis of the X-ray crystal structures of the RCs together with psec and fsec studies of charge separation coupled to nuclear motion in the system provides new insight into the problem. A psec study of PS I RCs has shown that the primary charge separation takes place between P700*. and the A-A0 complex. The three-dimensional structure of both the primary electron donor and acceptor shows a possible pathway for electron transfer between P700 and the A-A0 complex that is governed by nuclear motions. A fsec study of a coherent formation of the nuclear wavepacket on the potential energy surface of the excited state of the primary electron donor P* and of the charge separated state P+A− (where A is the primary electron acceptor) in native, pheophytin-modified and mutant reaction centers of Rhodobacter spaeroides was compared with X-ray and psec data for PS I RCs. A mechanism of the charge separation and stabilization of separated charges in PS I RCs is proposed.
KeywordsCharge Separation Rhodobacter Sphaeroides Nuclear Motion Primary Electron Donor Primary Charge Separation
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- Beens H and Weller A (1975) Excited molecular π-complexes in solution. In: Birks JB (ed) Organic Molecular Photophysics, Vol 11, pp 159–215. John Willey & Sons, LondonGoogle Scholar
- Bixon M, Jortner J, Plato M, and Michel-Beyerle ME (1988) Mechanism of the primary charge separation in bacterial photosynthetic reaction centers. In: Breton J and Vermeglio A (eds) The Photosynthetic Bacterial Reaction Center: Structure and Dynamics, pp 379–388. Plenum Press, New YorkGoogle Scholar
- Kuglstatter A, Hellwig P, Fritzsch G, Wachtveitl J, Oesterhelt D, Mantele W and Michel H (1999) Identification of a hydrogen bond in the Phe M197→Tyr mutant reaction center of the photosynthetic purple bacterium Rhodobacter sphaeroides by X-ray crystallography and FTIR spectroscopy. FEBS Lett 463: 169–174PubMedCrossRefGoogle Scholar
- Plato M, Lendzian F, Lubitz W, Trankle E and Mobius K (1988) Molecular orbital studies on the primary donor P960 in bacterial centers of Rps. viridis. In: Breton J and Vermeglio A (eds) The Photosynthetic Bacterial Reaction Center: Structure and Dynamics, pp 379–388. Plenum Press, New YorkGoogle Scholar
- Rischel C, Spiedel D, Ridge JP, Jones MR, Breton J, Lambry J-L, Martin J-L and Vos MH (1998) Low frequency vibrational modes in protein: charges induced by point-mutations in the protein–cofactor matrix of bacterial reaction centers. Proc Natl Acad Sci USA 95: 12306–12311PubMedCrossRefGoogle Scholar
- Shuvalov VA and Yakovlev AG (1998) Energy level of P+B− with respect to P* found from recombination fluorescence measurements in pheophytin-modified reaction centers. Membr Cell Biol (Moscow) 12: 563–569Google Scholar
- Yakovlev AG, Vasilieva LG, Shkuropatov AY, Bolgarina TI, Shkuropatova VA and Shuvalov VA (2003) Mechanism of charge separation and stabilization of separated charges in reaction centers of Chloroflexus aurantiacus and of YM210W(L) mutants of Rhodobacter sphaeroides excited by 20 fs pulses at 90 K. J Phys Chem A 107: 8330–8338CrossRefGoogle Scholar