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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
Author(s) -
Oh-oka Hirozo,
Kamei Shoichiro,
Matsubara Hiroshi,
Iwaki Masayo,
Itoh Shigeru
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)00433-a
Subject(s) - photosynthetic reaction centre , green sulfur bacteria , bacteriochlorophyll , cytochrome c , cytochrome , thermophile , sulfur , chemistry , chlorosome , hemeprotein , heme , stereochemistry , protein subunit , molecule , bacteria , purple bacteria , anaerobic bacteria , electron transfer , photochemistry , biochemistry , biology , photosynthesis , enzyme , organic chemistry , gene , genetics , mitochondrion
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.