Structure of the Primary Reactants in Photosystem II : Resonance Raman Studies of D1D2 Particles
Photosystem II reaction centers (RC) consist of D1 and D2 polypeptides and a bound cytochrome b 559. Isolated RC, named D1/D2 particles, contain 4–6 Chl a, 1 β-carotene and 1 or 2 cytochrome b 559 per two pheophytin a molecules (1). Polypeptides D1 and D2 exhibit marked homologies with the L and M subunits of the RC of purple bacteria, respectively (2). PS II shares a number of functional similarities with bacterial RCs. In these particles, absorption of a photon results in a rapid charge separation between the primary electron donor, P680, and a Pheo molecule; because of the lack of a secondary electron acceptor, relaxation of the D1/D2 reaction centers occurs through the formation of a 900 µs-lived triplet state involving Chl a molecule(s), named PR (3).
KeywordsTriplet State Difference Spectrum Resonance Raman Resonance Raman Spectrum Primary Electron Donor
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- 4]Lutz, M. and Robert, B. (1988) in Biological Applications of Raman Spectroscopy (Spiro, T.G. Ed.) pp. 347–411, Wiley, New York.Google Scholar
- 5]Robert, B., Nabedryk, E. and Lutz, M. (1989) in Time-Resolved Spectroscopy (Hester, R.E., Ed.) pp. 301–334, Wiley, London.Google Scholar
- 6]Zhou, Q., Robert, B. and Lutz, M. (1989) Biochim. Biophys. Acta (in press).Google Scholar