A native electrostatic environment near Q{sub B} is not sufficient to ensure rapid proton delivery in photosynthetic reaction centers.
Flash-induced absorption spectroscopy has been used to characterize Rhodobacter capsulatus reaction centers mutated in the secondary quinone acceptor site (Q{sub B}). We compared the wild-type, the L212Glu-L213Asp{yields}Ala-Ala photosynthetically incompetent double mutant (DM), and two photocompetent revertants, the DM+L217Arg{yields}Cys and the DM+M5Asn{yields}Asp strains. The electrostatic environment for Q{sub B}{sup -} is different in the two revertant strains. Only the L217Arg{yields}Cys mutation nearly restores the native electrostatic environment of Q{sub B}{sup -}. However, the level of recovery of the reaction center function, measured by the rates of second electron transfer and cytochrome c turnover, is quite incomplete in both strains. This shows that a wild-type-like electrostatic environment of Q{sub B}{sup -} cannot ensure on its own, rapid and efficient proton transfer to Q{sub B}{sup -}.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- ER
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 937958
- Report Number(s):
- ANL/CMB/JA-24717
- Journal Information:
- FEBS Lett., Journal Name: FEBS Lett. Journal Issue: 2 ; Apr. 28, 1997 Vol. 407; ISSN 0014-5793; ISSN FEBLAL
- Country of Publication:
- United States
- Language:
- ENGLISH
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