产酸克雷伯菌GS-4-08中一种无黄素氧不敏感偶氮还原酶的克隆与特性分析
Cloning and characterization of a Flavin-free oxygen-insensitive azoreductase from Klebsiella oxytoca GS-4-08.
作者信息
Hua Jing-Qiu, Yu Lei
机构信息
Department of Environmental Engineering, Nanjing Forestry University, Nanjing, 210037, China.
College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
出版信息
Biotechnol Lett. 2019 Mar;41(3):371-378. doi: 10.1007/s10529-019-02647-9. Epub 2019 Jan 11.
OBJECTIVES
This study reports the identification of a new bacterial azoreductase (AzoR) from Klebsiella oxytoca GS-4-08, its heterologous production in Escherichia coli and the decolorization of azo dyes.
RESULTS
The AzoR, as a flavin-free, oxygen-insensitive enzyme, has a molecular mass of 22 kDa and a high substrate specificity for methyl red (MR). In the presence of 5 mM of NADH, the enzyme activity for decolorization of 50 mg l of MR reached 5.61 μmol min mg protein. Double-reciprocal plots indicated that the NADH and MR reductions proceed by ping-pong mechanism. The calculated V was 8.17 μM min mg protein, and the AzoR retained over 75% of relative activity under temperature range from 20 to 50 °C.
CONCLUSION
This study for the first time identified an AzoR from Klebsiella oxytoca strain, which enabled efficient degradation of azo dyes by strain GS-4-08.
目的
本研究报道了从产酸克雷伯菌GS-4-08中鉴定出一种新的细菌偶氮还原酶（AzoR），其在大肠杆菌中的异源表达以及对偶氮染料的脱色作用。
结果
AzoR是一种不含黄素、对氧不敏感的酶，分子量为22 kDa，对甲基红（MR）具有高底物特异性。在5 mM NADH存在下，50 mg/l MR的脱色酶活性达到5.61 μmol/min/mg蛋白。双倒数作图表明，NADH和MR还原通过乒乓机制进行。计算得到的V为8.17 μM/min/mg蛋白，AzoR在20至50°C温度范围内保留超过75%的相对活性。
结论
本研究首次从产酸克雷伯菌菌株中鉴定出AzoR，其使GS-4-08菌株能够高效降解偶氮染料。
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