title: Halobacterium halobium cytochrome b-558 and cytochrome b-562: purification and some properties.
abstract: Four different membrane-bound b-type cytochromes were found to occur in Halobacterium halobium strain L-33, and two of them, b-558 and b-562, were purified to homogeneity. Cytochrome b-558 showed absorption peaks at 414 and 526 nm in the oxidized form, and peaks at 425, 528, and 558 nm in the reduced form. Its alpha peak at 558 nm in the reduced form was asymmetric with a shoulder at around 554 nm. At liquid nitrogen temperature, the a the alpha peak was split into two peaks at 549 and 556 nm which appeared to be the alpha peaks of cytochromes c and b, respectively. The cytochrome contained 1 mol of protoheme in 28,500 g, and was composed of one molecule each of two subunits with molecular masses of 15.4 and 11.7 kDa, respectively. The heme seemed bound to the larger subunit. The cytochrome was very autoxidizable and its redox potential at pH 8.0 was -75 mV. Cytochrome b-562 showed absorption peaks at 417 and 530 nm in the oxidized form and peaks at 431, 531, and 562 nm in the reduced form. The cytochrome was composed of only one polypeptide (25 kDa) and seemed to contain one protoheme molecule per molecule.
authors.affiliation: Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama.
authors.forename: T
authors.initials: T
authors.lastname: Fujiwara
authors.forename: Y
authors.initials: Y
authors.lastname: Fukumori
authors.forename: T
authors.initials: T
authors.lastname: Yamanaka
mesh_terms: D002462:Cell Membrane / Q000737:chemistry; D003080:Cold Temperature; D003573:Cytochrome b Group / Q000737:chemistry / Q000302:isolation & purification*; D029968:Escherichia coli Proteins; D019617:Halobacterium salinarum / Q000737:chemistry*; D006418:Heme / Q000032:analysis; D008970:Molecular Weight; D019255:NADPH Oxidases; D010084:Oxidation-Reduction; D013056:Spectrophotometry, Ultraviolet
chemical_list: D003573:Cytochrome b Group; D029968:Escherichia coli Proteins; D006418:Heme; C036888:cytochrome b558; C017850:cytochrome b562, E coli; D019255:NADPH Oxidases