点击次数：

论文类型：期刊论文

发表时间：2019-01-01

发表刊物：BIOTECHNOLOGY AND APPLIED BIOCHEMISTRY

收录刊物：PubMed、EI、SCIE

卷号：66

期号：1

页面范围：33-42

ISSN号：0885-4513

关键字：biotransformation; diverse substrate specificity; flavin mononucleotide reduction; nitro compounds,nitroreductase; Streptomyces

摘要：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 k(cat(app))/K-m(app) (0.234 mu M-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. (C) 2018 International Union of Biochemistry and Molecular Biology, Inc.