Two molecules of cytochrome c function as the electron donors to P840 in the reaction center complex isolated from a green sulfur bacterium, Chlorobium tepidum

FEBS Letters

Itoh, Shigeru¹  Iwaki, Masayo¹  Kamei, Shoichiro²  Matsubara, Hiroshi²  Oh-oka, Hirozo² 

[1] National Institute for Basic Biology, Okazaki 444, Japan;Department of Biology, Faculty of Science, Osaka University, Osaka 560, Japan

关键词: Cytochrome c;    Electron transfer;    Green sulfur bacteria;    Photosynthesis;    Reaction center;    Iron-sulfur center;    BChl;    bacteriochlorophyll;    RC;    reaction center;    PS;    photosystem;    P840;    primary electron donor;    PMSF;    phenylmethanesulfonyl fluoride;    Cys;    cysteine;    DTT;    dithiothreitol;    SDS-PAGE;    SDS-polyacrylamide gel electrophoresis;    N-;    amino-;    TMBZ;    3;    3′;    5;    5′-tetramethylbenzidine;    PscA and PscB;    core and iron-sulfur proteins encoded by pscA and pscB genes respectively in Chlorobium;   

DOI  :  10.1016/0014-5793(95)00433-A

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

A photoactive reaction center complex was isolated from a thermophilic green sulfur bacterium, Chlorobium tepidum under anaerobic conditions. The electron transfer occurred from heme c to the photo-oxidized reaction center chlorophyll, P840⁺, with a half time () of 110 or 340 μs at 24 or 12°C, respectively. Optical measurements under multiflash excitations indicated that two hemes function as the immediate electron donors to P840⁺. SDS-PAGE analysis of the RC complex in combination with the N-terminal amino acid sequence analyses revealed five subunit bands; a core protein (65 kDa), the light harvesting bacteriochlorophyll a protein (41 kDa), a protein with 2[4Fe-4S] clusters (31 kDa), monoheme cytochrome c (22 kDa), and a 18-kDa protein whose function is unknown. The reaction center complex, thus, contains two molecules of cytochrome c per P840.

【 授权许可】

Unknown