Ohshiro Takashi, Yamada Hiroko, Shimoda Tomohisa, Matsubara Toshiyuki, Izumi Yoshikazu
Department of Biotechnology, Tottori University, Tottori 680-8552, Japan.
Biosci Biotechnol Biochem. 2004 Aug;68(8):1712-21. doi: 10.1271/bbb.68.1712.
Flavin reductase is essential for the oxygenases involved in microbial dibenzothiophene (DBT) desulfurization. An enzyme of the thermophilic strain, Bacillus sp. DSM411, was selected to couple with DBT monooxygenase (DszC) from Rhodococcus erythropolis D-1. The flavin reductase was purified to homogeneity from Bacillus sp. DSM411, and the native enzyme was a monomer of M(r) 16 kDa. Although the best substrates were flavin mononucleotide and NADH, the enzyme also used other flavin compounds and acted slightly on nitroaromatic compounds and NADPH. The purified enzyme coupled with DszC and had a ferric reductase activity. Among the flavin reductases so far characterized, the present enzyme is the most thermophilic and thermostable. The gene coded for a protein of 155 amino acids with a calculated mass of 17,325 Da. The enzyme was overproduced in Escherichia coli, and the specific activity in the crude extracts was about 440-fold higher than that of the wild-type strain, Bacillus sp. DSM411.
黄素还原酶对于参与微生物二苯并噻吩（DBT）脱硫的加氧酶至关重要。从嗜热菌株芽孢杆菌属DSM411中选择一种酶，使其与红平红球菌D-1的DBT单加氧酶（DszC）偶联。从芽孢杆菌属DSM411中纯化得到了均一的黄素还原酶，天然酶是一种分子量为16 kDa的单体。尽管最佳底物是黄素单核苷酸和NADH，但该酶也使用其他黄素化合物，并且对硝基芳香化合物和NADPH有轻微作用。纯化后的酶与DszC偶联，并具有铁还原酶活性。在目前已鉴定的黄素还原酶中，该酶是最嗜热且最耐热的。该基因编码一个由155个氨基酸组成的蛋白质，计算分子量为17325 Da。该酶在大肠杆菌中过量表达，粗提物中的比活性比野生型菌株芽孢杆菌属DSM411高约440倍。
