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Proton transfer pathways and mechanism in bacterial reaction centers
Author(s) -
Paddock M.L.,
Feher G.,
Okamura M.Y.
Publication year - 2003
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(03)01149-9
Subject(s) - rhodobacter sphaeroides , proton , chemistry , quinone , photosynthetic reaction centre , proton coupled electron transfer , proton transport , photochemistry , electron transfer , stereochemistry , biochemistry , photosynthesis , membrane , physics , quantum mechanics
The focus of this minireview is to discuss the state of knowledge of the pathways and rates of proton transfer in the bacterial reaction center (RC) from Rhodobacter sphaeroides . Protons involved in the light driven catalytic reduction of a quinone molecule Q B to quinol Q B H 2 travel from the aqueous solution through well defined proton transfer pathways to the oxygen atoms of the quinone. Three main topics are discussed: (1) the pathways for proton transfer involving the residues: His‐H126, His‐H128, Asp‐L210, Asp‐M17, Asp‐L213, Ser‐L223 and Glu‐L212, which were determined by a variety of methods including the use of proton uptake inhibiting metal ions (e.g. Zn 2+ and Cd 2+ ); (2) the rate constants for proton transfer, obtained from a ‘chemical rescue’ study was determined to be 2×10 5 s −1 and 2×10 4 s −1 for the proton uptake to Glu‐L212 and Q B − , respectively; (3) structural studies of altered proton transfer pathways in revertant RCs that lack the key amino acid Asp‐L213 show a series of structural changes that propagate toward L213 potentially allowing Glu‐H173 to participate in the proton transfer processes.