title: A novel ferric reductase purified from Magnetospirillum gryphiswaldense MSR-1.
abstract: A ferric reductase was purified into an electrophoretically homologous state from Magnetospirillum gryphiswaldense MSR-1 strain. The enzyme was found within the cytoplasm and associated with the cytoplasmic membrane. The molecular weight of the purified enzyme was calculated as 16.1 kDa using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and was almost identical to that calibrated using agarose gel filtration chromatography. It was NADH-dependent and required flavin mononucleotide as a cofactor. The optimal reaction temperature and pH values were 30 degrees C and 6.5, respectively. The K(m) and Vmax values for ferric citrate were 45.1 microM: and 1.216 microM: min(-1), respectively. Though ferric reductase activity could be inhibited by Co(2+), Cu(2+), Mn(2+), and Zn(2+), even high concentrations of Mg(2+) ions have failed to accomplish such enzyme inhibition. Furthermore, the molecular weight, the N-terminal sequence, and the activity of ferric reductase from MSR-1 are not matching with the enzyme preparation obtained from an analogous strain M. magnetotacticum (MS-1). Therefore, it is concluded that the ferric reductase of M. grysphiwaldense and M. magnetotacticum strains are two different enzymes.
authors.affiliation: State Key Laboratories for Agrobiotechnology and College of Biological Sciences, China Agricultural University, Beijing, 100094, P R China.
authors.forename: Meng
authors.initials: M
authors.lastname: Xia
authors.forename: Jiang
authors.initials: J
authors.lastname: Wei
authors.forename: Yang
authors.initials: Y
authors.lastname: Lei
authors.forename: Li
authors.initials: L
authors.lastname: Ying
mesh_terms: D001426:Bacterial Proteins / Q000302:isolation & purification* / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D002850:Chromatography, Gel; D003067:Coenzymes / Q000494:pharmacology; D003593:Cytoplasm / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors; D004795:Enzyme Stability; D038181:FMN Reductase / Q000302:isolation & purification* / Q000378:metabolism; D005290:Ferric Compounds / Q000378:metabolism; D005486:Flavin Mononucleotide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism; D042201:Magnetospirillum / Q000201:enzymology*; D008670:Metals / Q000494:pharmacology; D008970:Molecular Weight; D009243:NAD / Q000378:metabolism; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D003067:Coenzymes; D004791:Enzyme Inhibitors; D005290:Ferric Compounds; D007527:Isoenzymes; D008670:Metals; D009243:NAD; C025314:ferric citrate; D005486:Flavin Mononucleotide; D038181:FMN Reductase; C023903:ferric citrate iron reductase