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- Title
Biochemical characteristics of a nitroreductase with diverse substrate specificity from Streptomyces mirabilis DUT001.
- Authors
Yang, Jun; Bai, Jing; Qu, Mingbo; Xie, Bo; Yang, Qing
- Abstract
A nitroreductase‐encoded gene from an efficient nitro‐reducing bacterium Streptomyces mirabilis DUT001, named snr, was cloned and heterogeneously expressed in Escherichia coli. The purified Streptomyces nitroreductase SNR was a homodimer with an apparent subunit molecular weight of 24 kDa and preferred NADH to NADPH as a cofactor. By enzyme incubation and isothermal calorimetry experiments, flavin mononucleotide (FMN) was found to be the preferred flavin cofactor; the binding process was exothermic and primarily enthalpy driven. The enzyme can reduce multiple nitro compounds and flavins, including antibacterial drug nitrofurazone, priority pollutants 2,4‐dinitrotoluene and 2,4,6‐trinitrotoluene, as well as key chemical intermediates 3‐nitrophthalimide, 4‐nitrophthalimide, and 4‐nitro‐1,8‐naphthalic anhydride. Among the substrates tested, the highest activity of kcat(app)/Km(app) (0.234 μM−1 Sec−1) was observed for the reduction of FMN. Multiple sequence alignment revealed that the high FMN reduction activity of SNR may be due to the absence of a helix, constituting the entrance to the substrate pocket in other nitroreductases.
- Subjects
NITROREDUCTASES; STREPTOMYCES; ESCHERICHIA coli; MOLECULAR cloning; CALORIMETRY
- Publication
Biotechnology & Applied Biochemistry, 2019, Vol 66, Issue 1, p33
- ISSN
0885-4513
- Publication type
Article
- DOI
10.1002/bab.1692