title: Highly purified photosynthetic reaction center (PscA/cytochrome c551)2 complex of the green sulfur bacterium Chlorobium limicola.
abstract: The photosynthetic reaction center (RC) complex that forms a homodimer of core and cytochrome c subunits was isolated from Chlorobium limicola f. thiosulfatophilum, strain Larsen. The complex showed only two subunit bands at 68 (PscA core) and 21 kDa (cytochrome c551) on SDS-PAGE analysis, indicating the complete deletion of the light-harvesting bacteriochlorophyll a (BChl a) protein as well as the iron-sulfur protein. It contained 27 +/- 3 molecules of BChl a, 7 +/- 1 Chl-670, 3 +/- 1 carotenoids, and 1.6 +/- 0.1 c-type hemes per the primary electron donor P840. The complex showed a light-induced charge separation and recombination between P840 and the acceptor Chl-670 at 77 K as follows: P840*Chl-670-->P840+Chl-670(-)-->P840TChl-670-->P84 0 Chl-670. Pigment compositions and their function in the (PscA/cytochrome c551)2 complex were studied by absorption, circular dichroism, and fluorescence spectroscopy.
authors.affiliation: Department of Biology, Faculty of Science, Osaka University, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Oh-oka
authors.forename: S
authors.initials: S
authors.lastname: Kakutani
authors.forename: S
authors.initials: S
authors.lastname: Kamei
authors.forename: H
authors.initials: H
authors.lastname: Matsubara
authors.forename: M
authors.initials: M
authors.lastname: Iwaki
authors.forename: S
authors.initials: S
authors.lastname: Itoh
mesh_terms: D001419:Bacteria / Q000201:enzymology*; D001426:Bacterial Proteins; D002942:Circular Dichroism; D003574:Cytochrome c Group / Q000737:chemistry*; D006090:Gram-Negative Bacteria / Q000737:chemistry; D045342:Light-Harvesting Protein Complexes; D008970:Molecular Weight; D010777:Photochemistry; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D045331:Photosystem I Protein Complex; D013050:Spectrometry, Fluorescence; D013057:Spectrum Analysis
chemical_list: D001426:Bacterial Proteins; D003574:Cytochrome c Group; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; C096017:PscA protein, green sulfur bacteria; C017167:cytochrome C(551)