title: Nitroreductase from Salmonella typhimurium: characterization and catalytic activity.
abstract: The biocatalytic activity of nitroreductase from Salmonella typhimurium (NRSal) was investigated for the reduction of alpha,beta-unsaturated carbonyl compounds, nitroalkenes, and nitroaromatics. The synthesized gene was subcloned into a pET28 overexpression system in E.coli BL21 strain, and the corresponding expressed protein was purified to homogeneity with 15% protein mass yield and 41% of total activity recovery. NRSal showed broad substrate acceptance for various nitro compounds such as 1-nitrocyclohexene and aliphatic nitroalkenes (alkene reductase activity), as well as nitrobenzene (nitroreductase activity), with substrate conversion efficiency of > 95%. However, the reduction of enones was generally low, proceeding albeit with high stereoselectivity. The efficient biocatalytic reduction of substituted nitroalkenes provides a route for the preparation of the corresponding nitroalkanes. NRSal also demonstrated the first single isolated enzyme-catalyzed reduction of nitrobenzene to aniline through the formation of nitrosobenzene and phenylhydroxylamine as intermediates. However, chemical condensation of the two intermediates to produce azoxybenzene currently limits the yield of aniline.
authors.affiliation: School of Chemical and Biomolecular Engineering, Parker H. Petit Institute of Bioengineering and Biosciences, Georgia Institute of Technology, 315 Ferst Drive, Atlanta, GA 30332-0363, USA.
authors.forename: Yanto
authors.initials: Y
authors.lastname: Yanto
authors.forename: Mélanie
authors.initials: M
authors.lastname: Hall
authors.forename: Andreas S
authors.initials: AS
authors.lastname: Bommarius
mesh_terms: D000595:Amino Acid Sequence; D000814:Aniline Compounds / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D008969:Molecular Sequence Data; D009574:Nitro Compounds / Q000378:metabolism*; D009578:Nitrobenzenes / Q000378:metabolism; D009601:Nitroreductases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000201:enzymology* / Q000235:genetics; D016415:Sequence Alignment; D013379:Substrate Specificity; D015854:Up-Regulation
chemical_list: D000814:Aniline Compounds; D009574:Nitro Compounds; D009578:Nitrobenzenes; C036077:nitrobenzene; D009601:Nitroreductases; C023650:aniline