title: NMR studies of a ferredoxin from Haloferax mediterranei and its physiological role in nitrate assimilatory pathway.
abstract: Haloferax mediterranei is a halophilic archaeon that can grow in aerobic conditions with nitrate as sole nitrogen source. The electron donor in the aerobic nitrate reduction to ammonium was a ferredoxin. This ferredoxin has been purified and characterised. Air-oxidized H. mediterranei ferredoxin has a UV-visible absorption spectra typical of 2Fe-type ferredoxins with an A420/A280 of 0.21. The nuclear magnetic resonance (NMR) spectra of the ferredoxin showed similarity to those of ferredoxins from plant and bacteria, containing a [2Fe-2S] cluster. The physiological function of ferredoxin might be to serve as an electron donor for nitrate reduction to ammonium by assimilatory nitrate (EC 1.6.6.2) and nitrite reductases (EC 1.7.7.1). The apparent molecular weight (Mr) of the ferredoxin was estimated to be 21 kDa on SDS-polyacrylamide gel electrophoresis (SDS-PAGE).
authors.affiliation: División de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Alicante, Aptd. Correus 99, E-03080 Alicante, Spain.
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Martínez-Espinosa
authors.forename: Frutos C
authors.initials: FC
authors.lastname: Marhuenda-Egea
authors.forename: Antonio
authors.initials: A
authors.lastname: Donaire
authors.forename: María José
authors.initials: MJ
authors.lastname: Bonete
mesh_terms: D005288:Ferredoxins / Q000737:chemistry* / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism*; D019623:Haloferax mediterranei / Q000737:chemistry* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D009566:Nitrates / Q000378:metabolism; D010084:Oxidation-Reduction; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012965:Sodium Chloride / Q000737:chemistry; D013696:Temperature
chemical_list: D005288:Ferredoxins; D009566:Nitrates; D000644:Quaternary Ammonium Compounds; D012965:Sodium Chloride