title: [Dependence of the structure of malate dehydrogenase on the type of metabolism in fresh water filamentous colorless sulfur bacteria of the Beggiatoa species].
abstract: Major pathways of carbon metabolism were studied in strains D-402 and D-405 of freshwater colorless sulfur bacteria of the genus Beggiatoa grown organotrophically and mixotrophically. The bacteria were found to possess all the enzymes of the tricarboxylic acid (TCA) and glyoxylate cycles. When organotrophic growth changed to mixotrophic one, the activity of the TCA cycle enzymes decreased 2- to 3-fold, but the activity of enzymes of the glyoxylate cycle increased threefold. It follows that, in the oxidation of thiosulfate, organic compounds no longer play the leading part in the energy metabolism, and most of electrons that enter the electron transport chain (ETC) derive from inorganic sulfur compounds. A connection was established between the structure and kinetic characteristics of malate dehydrogenase--an enzyme of the TCA and glyoxylate cycles--and the type of carbon metabolism in the strains studied. Malate dehydrogenase in organotrophically grown cells of strains D-402 and D-405 is dimeric, whereas in strain D-402 grown mixotrophically it is tetrameric.
authors.affiliation: Voronezh State University, Voronezh, 394893 Russia.
authors.forename: I Iu
authors.initials: IIu
authors.lastname: Stepanova
authors.forename: A T
authors.initials: AT
authors.lastname: Eprintsev
authors.forename: M I
authors.initials: MI
authors.lastname: Falaleeva
authors.forename: N V
authors.initials: NV
authors.lastname: Parfenova
authors.forename: M Iu
authors.initials: MIu
authors.lastname: Grabovich
authors.forename: V Iu
authors.initials: VIu
authors.lastname: Patritskaia
authors.forename: G A
authors.initials: GA
authors.lastname: Dubinina
mesh_terms: D002952:Citric Acid Cycle; D004579:Electron Transport; D004591:Electrophoresis, Polyacrylamide Gel; D005618:Fresh Water; D007700:Kinetics; D008291:Malate Dehydrogenase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011487:Protein Conformation; D041962:Thiotrichaceae / Q000201:enzymology / Q000378:metabolism*; D014871:Water Microbiology
chemical_list: D008291:Malate Dehydrogenase