Effect of the in situ electrochemical oxidation on the pigment-protein arrangement and energy transfer in light-harvesting complex from Rhodobacter sphaeroides 601.
The oxidation of bacteriochlorophylls (BChls) in peripheral light-harvesting complexes (LH2) from Rhodobacter sphaeroides was investigated by spectroelectrochemistry of absorption, fluorescence emission, and femtosecond (fs) pump-probe, with the aim obtaining information about the effect of in situ electrochemical oxidation on the pigment-protein arrangement and energy transfer within LH2. The experimental results revealed that: (a) the generation of the BChl radical cation in both B800 and B850 rings dramatically induced bleaching of the characteristic absorption in the NIR region and quenching of the fluorescence emission from the B850 ring for the electrochemical oxidized LH2; (b) the BChl-B850 radical cation might act as an additional channel to compete with the unoxidized BChl-B850 molecules for rapidly releasing the excitation energy, however the B800-B850 energy transfer rate remained almost unchanged during the oxidation process.
Liu
Weimin
W
Physics Department, Fudan University, Shanghai 200433, China.
Lu
Yidong
Y
Liu
Yuan
Y
Liu
Kangjun
K
Yan
Yongli
Y
Kong
Jilie
J
Xu
Chunhe
C
Qian
Shixiong
S
D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D004563:Electrochemistry; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods; D007259:Infrared Rays; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D010084:Oxidation-Reduction; D010860:Pigments, Biological / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D012242:Rhodobacter sphaeroides / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*
C081521:B800-850 light-harvesting complex, bacteria; D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; D010860:Pigments, Biological