title: Membrane-associated c-type cytochromes from the green sulfur bacterium Chlorobium limicola forma thiosulfatophilum: purification and characterization of cytochrome c553.
abstract: Tetraheme cytochromes involved in photosynthetic electron transport have previously been described associated with the reaction centers of purple photosynthetic bacteria; however, similar heme proteins have not until now been characterized in the phylogenetically distinct green sulfur bacteria. In this paper we describe the first isolation and characterization of a multitheme, membrane-associated cytochrome from a green sulfur bacterium, Chlorobium limicola forma thiosulfatophilum. We show that this cytochrome contains a single polypeptide of 32 kDa apparent molecular mass on SDS-PAGE and has a characteristic broad alpha-band absorption at 553 nm. By both low-temperature absorption and electron paramagnetic resonance spectroscopy, we demonstrate that there are at least four distinct heme groups.
authors.affiliation: Section de Biophysique des Protéines et des Membranes, DBCM/CEA, Gif sur Yvette, France.
authors.forename: D
authors.initials: D
authors.lastname: Albouy
authors.forename: J N
authors.initials: JN
authors.lastname: Sturgis
authors.forename: U
authors.initials: U
authors.lastname: Feiler
authors.forename: W
authors.initials: W
authors.lastname: Nitschke
authors.forename: B
authors.initials: B
authors.lastname: Robert
mesh_terms: D019414:Chlorobi / Q000201:enzymology*; D003574:Cytochrome c Group / Q000737:chemistry* / Q000302:isolation & purification*; D008280:Magnetics; D008565:Membrane Proteins / Q000737:chemistry* / Q000302:isolation & purification*; D008970:Molecular Weight; D055095:Optics and Photonics; D013053:Spectrophotometry
chemical_list: D003574:Cytochrome c Group; D008565:Membrane Proteins; C083951:cytochrome c553