Initial electron-transfer events in photosynthetic bacteria

Abstract The electron transfer from the primary donor special pair to the primary acceptor bacteriopheophytin in bacterial photosynthesis, as probed by femtosecond spectroscopy, is discussed in terms of the following four issues: unidirectionality; single-step superexchange versus the two-step sequential mechanism; the temperature dependence of the electron-transfer rate; and the improved methodology for examining the primary events in photosynthesis. New methods are still required to address the recently observed non-single exponential decay of the initial excited state of photosynthesis. Without additional information, the mechanism of the primary charge separation chemistry will remain unsettled.