title: Tuning of the redox potential of the primary electron donor in reaction centres of purple bacteria: effects of amino acid polarity and position.
abstract: Mutation of residues His L168 and Phe M197 in the reaction centre from Rhodobacter sphaeroides has an unusually strong effect on the mid-point redox potential (E(m)) of the pair of bacteriochlorophylls that form the primary donor of electrons, tuning E(m) over a range of nearly 250 mV. This effect is correlated to the accompanying change in the permanent dipole of the L168 or M197 residue, suggesting it is mediated by changes in charge-dipole interactions. Comparisons with mutations made at a variety of other positions show that this correlation is particular to this residue pair, perhaps reflecting their proximity to the ring I regions of the dimer bacteriochlorophylls that form the overlap region between these molecules.
authors.affiliation: Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, S10 2UH, Sheffield, UK.
authors.forename: Diane
authors.initials: D
authors.lastname: Spiedel
authors.forename: Michael R
authors.initials: MR
authors.lastname: Jones
authors.forename: Bruno
authors.initials: B
authors.lastname: Robert
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D004583:Electrons; D006639:Histidine / Q000737:chemistry; D007930:Leucine / Q000737:chemistry; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010649:Phenylalanine / Q000737:chemistry; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D011487:Protein Conformation; D012242:Rhodobacter sphaeroides / Q000737:chemistry / Q000378:metabolism*; D014443:Tyrosine / Q000737:chemistry
chemical_list: D000596:Amino Acids; D045322:Photosynthetic Reaction Center Complex Proteins; D014443:Tyrosine; D010649:Phenylalanine; D006639:Histidine; D007930:Leucine