Primary charge separation in bacterial photosynthesis: oxidized chlorophylls and reduced pheophytin.
AUTOR(ES)
Fajer, J
RESUMO
Bacteriopheophytin, the magnesium-free base of bacteriochlorophyll, undergoes reversible one-electron reduction in organic solvents to yield an anionic free radical with characteristic optical and electron spin resonance spectra. The reduction potential of bacteriopheophytin, E1/2 approximately --0.55 V against a normal hydrogen electrode, compared to E1/2 approximately --0.85 V for bacteriochlorophyll, renders it a likely electron acceptor in the primary charge separation of photosynthesis. Comparison of these data with picosecond optical changes recently observed upon pulsed laser excitation of bacterial reaction centers leads us to propose that bacteriopheophytin is indeed a transient electron acceptor and that the primary charge separation of bacterial photosynthesis occurs between the bacteriochlorophyll complex P870 and bacteriopheophytin to yield the radicals of the oxidized chlorophyll dimer cation and reduced pheophytin anion.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=388853Documentos Relacionados
- Tracing charge separation events in photosynthesis: anomalous photovoltage polarity events explained.
- Long-time quantum simulation of the primary charge separation in bacterial photosynthesis.
- The triplet state in bacterial photosynthesis: Possible mechanisms of the primary photo-act
- Primary acceptor in bacterial photosynthesis: obligatory role of ubiquinone in photoactive reaction centers of Rhodopseudomonas spheroides.
- Role of charge-transfer states in bacterial photosynthesis