Nojiri H, Nam J W, Kosaka M, Morii K I, Takemura T, Furihata K, Yamane H, Omori T
Biotechnology Research Center, Science University of Tokyo, Japan.
J Bacteriol. 1999 May;181(10):3105-13. doi: 10.1128/JB.181.10.3105-3113.1999.
Carbazole 1,9a-dioxygenase (CARDO) from Pseudomonas sp. strain CA10 is a multicomponent enzyme that catalyzes the angular dioxygenation of carbazole, dibenzofuran, and dibenzo-p-dioxin. It was revealed by gas chromatography-mass spectrometry and 1H and 13C nuclear magnetic resonance analyses that xanthene and phenoxathiin were converted to 2,2',3-trihydroxydiphenylmethane and 2,2',3-trihydroxydiphenyl sulfide, respectively. Thus, for xanthene and phenoxathiin, angular dioxygenation by CARDO occurred at the angular position adjacent to the oxygen atom to yield hetero ring-cleaved compounds. In addition to the angular dioxygenation, CARDO catalyzed the cis dihydroxylation of polycyclic aromatic hydrocarbons and biphenyl. Naphthalene and biphenyl were converted by CARDO to cis-1, 2-dihydroxy-1,2-dihydronaphthalene and cis-2,3-dihydroxy-2, 3-dihydrobiphenyl, respectively. On the other hand, CARDO also catalyzed the monooxygenation of sulfur heteroatoms in dibenzothiophene and of the benzylic methylenic group in fluorene to yield dibenzothiophene-5-oxide and 9-hydroxyfluorene, respectively. These results indicate that CARDO has a broad substrate range and can catalyze diverse oxygenation: angular dioxygenation, cis dihydroxylation, and monooxygenation. The diverse oxygenation catalyzed by CARDO for several aromatic compounds might reflect the differences in the binding of the substrates to the reaction center of CARDO.
来自假单胞菌属CA10菌株的咔唑1,9a -双加氧酶（CARDO）是一种多组分酶，可催化咔唑、二苯并呋喃和二苯并 - p -二恶英的角向双加氧反应。通过气相色谱 - 质谱分析以及1H和13C核磁共振分析表明，呫吨和吩恶噻嗪分别转化为2,2',3 -三羟基二苯甲烷和2,2',3 -三羟基二苯硫醚。因此，对于呫吨和吩恶噻嗪，CARDO的角向双加氧反应发生在与氧原子相邻的角位，生成杂环裂解化合物。除了角向双加氧反应外，CARDO还催化多环芳烃和联苯的顺式二羟基化反应。萘和联苯分别被CARDO转化为顺式 - 1,2 -二羟基 - 1,2 -二氢萘和顺式 - 2,3 -二羟基 - 2,3 -二氢联苯。另一方面，CARDO还催化二苯并噻吩中硫杂原子的单加氧反应以及芴中苄基亚甲基的单加氧反应，分别生成二苯并噻吩 - 5 -氧化物和9 -羟基芴。这些结果表明，CARDO具有广泛的底物范围，并且可以催化多种氧化反应：角向双加氧反应、顺式二羟基化反应和单加氧反应。CARDO对几种芳香族化合物催化的多种氧化反应可能反映了底物与CARDO反应中心结合的差异。
