Preliminary Characterization of pAT-3, a Symmetry Enhanced Reaction Center Mutant of Rhodobacter capsulatus
A Rhodobacter capsulatus reaction center mutant has been constructed in which residues M187 through M203 have been replaced by the homologous region of the L polypeptide (L160 through L176). This mutant expresses reaction centers, grows photosynthetically and undergoes electron transfer forming P+QA − with high quantum yield. Absorption and Stark measurements indicate a significant alteration in the electronic nature of the special pair, and time-resolved fluorescence measurements suggest changes in the photochemistry of the initial electron transfer reaction. Finally, the redox potential of the special pair has apparently been increased significantly in this mutant to greater than 500 mV.
KeywordsChlorophyll Recombination Titration Polypeptide Photosynthesis
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