title: Purification and characterization of a monomeric isocitrate dehydrogenase from the sulfate-reducing bacterium Desulfobacter vibrioformis and demonstration of the presence of a monomeric enzyme in other bacteria.
abstract: NADP(+)-specific isocitrate dehydrogenase (EC 1.1.1.42) was purified to homogeneity from the sulfate-reducing bacterium Desulfobacter vibrioformis, and shown to be a monomeric protein with a molecular mass of 80 kDa. The pH and temperature optima were 8.5 and 45 degrees C, respectively. The N-terminal amino acid sequence (Thr, Glu, Thr, Ile, Arg, Trp, Thr, X, Thr, Asp, Glu, Ala, Pro, Leu, Leu, Ala, Thr) showed similarity with that of other known monomeric isocitrate dehydrogenases. Catalytically active isocitrate dehydrogenase from D. vibrioformis was obtained by activity staining after SDS-PAGE and removal of SDS from the gel. This technique revealed a NADP(+)-dependent monomeric enzyme in other Desulfobacter spp., Desulfuromonas acetoxidans and Chlorobium tepidium. These findings imply that monomeric isocitrate dehydrogenases are present in distantly related bacteria and indicate an early evolution of monomeric isocitrate dehydrogenases in the bacterial lineage.
authors.affiliation: Department of Microbiology, University of Bergen, Norway. ida.steen@medfa.uib.no
authors.forename: I H
authors.initials: IH
authors.lastname: Steen
authors.forename: M S
authors.initials: MS
authors.lastname: Madsen
authors.forename: N K
authors.initials: NK
authors.lastname: Birkeland
authors.forename: T
authors.initials: T
authors.lastname: Lien
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D005075:Biological Evolution; D002952:Citric Acid Cycle / Q000502:physiology; D004591:Electrophoresis, Polyacrylamide Gel; D007521:Isocitrate Dehydrogenase / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D008969:Molecular Sequence Data; D009249:NADP / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D016999:Sulfur-Reducing Bacteria / Q000201:enzymology* / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D009249:NADP; D007521:Isocitrate Dehydrogenase