title: Purification and characterization of dissimilatory nitrate reductase from a denitrifying halophilic archaeon, Haloarcula marismortui.
abstract: Dissimilatory nitrate reductase was purified from a denitrifying halophilic archaeon, Haloarcula marismortui, to an electrophoretically homogeneous state. The purified enzyme was inferred to be a homotetramer composed of a 63 kDa polypeptide. The electron paramagnetic resonance spectrum of the purified enzyme revealed typical rhombic signals which were ascribed to Mo(V) in the Mo-molybdopterin complex. Like the bacterial membrane-bound (Nar-) enzyme, the purified enzyme supported the catalysis of chlorate. The enzyme was activated in extreme saline conditions and the values of k(cat) and K(m) toward nitrate were 145 s(-1) and 79 microM, respectively, in the presence of 2.0 M NaCl.
authors.affiliation: Department of Biology and Geosciences, Faculty of Science, Shizuoka University, 836 Ohya, Shizuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yoshimatsu
authors.forename: T
authors.initials: T
authors.lastname: Sakurai
authors.forename: T
authors.initials: T
authors.lastname: Fujiwara
mesh_terms: D001419:Bacteria / Q000201:enzymology; D002384:Catalysis / Q000187:drug effects; D002704:Chlorates / Q000378:metabolism; D003067:Coenzymes / Q000032:analysis; D004578:Electron Spin Resonance Spectroscopy; D004789:Enzyme Activation / Q000187:drug effects; D004795:Enzyme Stability / Q000187:drug effects; D019614:Haloarcula marismortui / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D007501:Iron / Q000032:analysis; D008667:Metalloproteins / Q000032:analysis; D008970:Molecular Weight; D008982:Molybdenum / Q000032:analysis; D000090006:Molybdenum Cofactors; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism*; D010084:Oxidation-Reduction; D020836:Protein Structure, Quaternary; D011621:Pteridines / Q000032:analysis; D012965:Sodium Chloride / Q000494:pharmacology; D013455:Sulfur / Q000032:analysis; D013816:Thermodynamics
chemical_list: D002704:Chlorates; D003067:Coenzymes; D007501:Iron; D008667:Metalloproteins; D008982:Molybdenum; D000090006:Molybdenum Cofactors; D050901:Nitrate Reductase; D009565:Nitrate Reductases; D009566:Nitrates; D009573:Nitrites; D011621:Pteridines; D012965:Sodium Chloride; D013455:Sulfur; C022261:molybdopterin; C022842:chloric acid