Structure and Function of the Cytochrome c 2 :Reaction Center Complex from Rhodobacter sphaeroides

摘要: In purple non-sulfur photosynthetic bacteria, a c-type heme protein, cytochrome (Cyt) c 2, serves as the electron donor to reaction center (RC) which is site of initial photochemical transfer. The second order rate transfer from Cyt 2 RC diffusion limited and optimized facilitate through apparatus. This review summarizes X-ray crystal structure 2:RC complex Rhodobacter (Rba.) sphaeroides studies based on that elucidate molecular basis for role in shows cofactor van der Waals contact with close proximity bacteriochlorophyll dimer, primary donor. binding interface region includes: a) solvent-separated long-range electrostatic interactions between complementary charged residues play protein docking binding, b) small central short-range interactions, including hydrophobic, hydrogen bonding, cation-π interaction, surface strong electronic coupling cofactors rapid inter-protein Both types contribute binding. However, two have markedly different effects kinetics. change constant by changing association but not bound state. do affect dissociation well strength allow sufficiently fast oxidized does limit cyclic