谷氨酸棒杆菌中谷氨酰胺合成酶的克隆表达及固定化
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Cloning,Expression and Immobilization of Glutamine Synthetase from Corynebacterium glutamicum
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    摘要:

    对谷氨酸棒杆菌(C. glutamicum)来源的谷氨酰胺合成酶进行腺苷酰化位点定点突变,并在大肠杆菌中进行异源表达,得到的重组酶活为6.215 U/mg。分离纯化重组突变酶后,对其固定化条件及固定化酶的性质进行研究。结果得到固定化条件为:以LX?鄄1000EP树脂作为固定载体,载体量 0.176 g/U、pH 值8.0、温度 30 ℃、吸附时间 16 h。固定化酶活力达到 3.658 U/g,酶活回收率达到 67.17%。重组酶固定化后,反应最适温度没有变化,最适pH略向碱性偏移,储藏稳定性提高,转化谷氨酸生产谷氨酰胺的水平与游离酶相当,对50 mmol/L谷氨酸的转化率为92.83%,为酶法生产谷氨酰胺后续研究提供了参考。

    Abstract:

    The glutamine synthetase encoded gene of Corynebacterium glutamicum was cloned and mutated on polyadenylation sites,followed by heterogeneous expression in E. coli with high enzyme activity of 6.215 U/mg. The recombinant mutant enzyme(GS') was purified,and LX1000-EP resin was employed as the immobilization carrier. The results showed that the optimal conditions for immobilization were in the following:0.176 g carriers/1 U enzyme,pH 8.0,25 ℃ and 16 h. Under the above conditions the highest bioactivity (3.658 U/g) of immobilized GS' was achieved with high active recovery rate of 67.17%. Compared with free enzyme,the immobilized GS has the same optimal temperature and stability,however the optimal pH was slightly increased. The immobilized GS has the same conversion rate of 92.83% when 50 mmol/L glutamate was added in the bioconversion system. This work is useful for further large-scale bioproduction of glutamine.

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曹慧萍,郑璞,唐云平,徐志南.谷氨酸棒杆菌中谷氨酰胺合成酶的克隆表达及固定化[J].食品与生物技术学报,2016,35(8):883-889.

CAO Huiping, ZHENG Pu, TANG Yunping, XU Zhinan. Cloning,Expression and Immobilization of Glutamine Synthetase from Corynebacterium glutamicum[J]. Journal of Food Science and Biotechnology,2016,35(8):883-889.

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  • 在线发布日期: 2016-11-01
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