title: Nitrate reductase whole-cell assay: side effects associated with the use of benzyl viologen.
abstract: A comparative examination of reduced methyl [MV·](+) and benzyl [BV·](+) viologens (as artificial electron donors for quantitative estimation of the respiratory periplasmic (Nap) and membrane-embedded (Nar) nitrate reductases) using a newly constructed nap mutant strain of Paracocccus denitrificans was done. The activity with [MV·](+) was high in whole-cell assays, confirming that this compound donates electrons to Nar. Initial rates of the more lipophilic [BV·](+) were considerably lower, which was interpreted to be caused by an inhibition of the active transport of nitrate into the cells. Anionophoric activity of [BV·](+) was detectable but too low to effectively circumvent the inhibition of nitrate transporter.
authors.affiliation: Department of Biochemistry, Faculty of Science, Masaryk University, Kamenice 5, CZ-62500, Brno, Czech Republic.
authors.forename: A
authors.initials: A
authors.lastname: Illichmanová
authors.forename: M
authors.initials: M
authors.lastname: Janů
authors.forename: V
authors.initials: V
authors.lastname: Sedláček
authors.forename: I
authors.initials: I
authors.lastname: Kučera
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001594:Benzyl Viologen / Q000378:metabolism*; D004579:Electron Transport; D007700:Kinetics; D050901:Nitrate Reductase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D010084:Oxidation-Reduction; D041902:Rhodobacteraceae / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D059010:Single-Cell Analysis
chemical_list: D001426:Bacterial Proteins; D009566:Nitrates; D001594:Benzyl Viologen; D050901:Nitrate Reductase