title: An octameric prokaryotic glutamine synthetase from the haloarchaeon Haloferax mediterranei.
abstract: The glutamine synthetase (EC 6.3.1.2) from the haloarchaeon Haloferax mediterranei has been purified and characterized in order to understand the ammonium assimilation in haloarchaea. Based on sodium dodecyl sulfate polyacrylamide gel electrophoresis and gel-filtration chromatography, the enzyme consists of eight subunits of 51.7 kDa, suggesting that this enzyme belongs to the glutamine synthetase type II. The purified enzyme has been characterized with respect to its optimum temperature (45 degrees C) and pH value (8.0). The optimal NaCl or KCl concentrations for the reaction were 0.5 and 0.25 M, respectively. The effect of l-methionine-d, l-sulphoximine and different divalent metal ions has also been tested. The glutamine synthetase presented here is unusual; it shows the typical characteristic of eukaryotic and soil bacteria glutamine synthetases.
authors.affiliation: División de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Alicante, Alicante, Spain.
authors.forename: Rosa María
authors.initials: RM
authors.lastname: Martínez-Espinosa
authors.forename: Julia
authors.initials: J
authors.lastname: Esclapez
authors.forename: Vanesa
authors.initials: V
authors.lastname: Bautista
authors.forename: María José
authors.initials: MJ
authors.lastname: Bonete
mesh_terms: D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability; D005974:Glutamate-Ammonia Ligase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000302:isolation & purification; D019623:Haloferax mediterranei / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D008715:Methionine / Q000494:pharmacology; D008717:Methionine Sulfoximine / Q000494:pharmacology; D011189:Potassium Chloride / Q000737:chemistry; D020836:Protein Structure, Quaternary; D021122:Protein Subunits / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D013696:Temperature
chemical_list: D004791:Enzyme Inhibitors; D021122:Protein Subunits; D008717:Methionine Sulfoximine; D012965:Sodium Chloride; D011189:Potassium Chloride; D008715:Methionine; C083818:glutamine synthetase 2; D005974:Glutamate-Ammonia Ligase