A novel method for enzymatic synthesis of L-theanine using copper(Ⅱ)-L-glutamine[Cu(Gln)2]as donor substrate was proposed.The structure of Cu(Gln)2 was identified by infrared spectrum analysis and its stability was a...A novel method for enzymatic synthesis of L-theanine using copper(Ⅱ)-L-glutamine[Cu(Gln)2]as donor substrate was proposed.The structure of Cu(Gln)2 was identified by infrared spectrum analysis and its stability was also investigated under the reaction conditions.The enzymatic synthesis of L-theanine catalyzed by γ-glutamyltranspeptidase was carried out by using Cu(Gln)2 and L-glutamine as donor substrate respectively,and the product yield and conversion rate of donor substrate were compared under the conditions of different ratios of donor and acceptor.The results showed that the transpeptidation reaction could be effectively enhanced by using Cu(Gln)2 as donor substrate.The conversion rate of donor would increase by 51.5%,44.9% and 27.1% under different reaction conditions,compared to that using L-Gln as donor substrate.When the molar ratio of donor to acceptor was 6∶100,a higher donor conversion of 71.3% was obtained.展开更多
在谷氨酸棒状杆菌( Corynebacterium glutamicum )SNK118中表达NADP +依赖型的3-磷酸甘油醛脱氢酶编码基因,提高胞内NADPH水平,以提高 L -精氨酸( L -Arginine)和 L -鸟氨酸(L-Ornithine)发酵产量。通过NCBI数据库检索,选取了3个不同来...在谷氨酸棒状杆菌( Corynebacterium glutamicum )SNK118中表达NADP +依赖型的3-磷酸甘油醛脱氢酶编码基因,提高胞内NADPH水平,以提高 L -精氨酸( L -Arginine)和 L -鸟氨酸(L-Ornithine)发酵产量。通过NCBI数据库检索,选取了3个不同来源的3-磷酸甘油醛脱氢酶编码基因。经测定酶活力,最终选择糖丁基梭菌( Clostridium saccharobutylicum) DSM13864来源的NADP +依赖型的3-磷酸甘油醛脱氢酶基因( CsgapC )。构建了产 L -精氨酸的重组菌SNK118/pXMJ19- CsgapC,当摇瓶发酵70 h时产 L -精氨酸11.55 g/L,糖酸转化率0.13 g/g,与对照菌SNK118/pXMJ19相比,精氨酸产量和糖酸转化率分别提高了26%和10.2%。在 L -鸟氨酸生产菌株SNK118Δ argF Δ argR 中重组表达 CsgapC,重组菌SNK118Δ argF Δ argR /pXMJ19- CsgapC 摇瓶发酵70 h产 L -鸟氨酸27.76 g/L,糖酸转化率0.274 g/g,与对照菌SNK118Δ argF Δ argR /pXMJ19相比, L -鸟氨酸产量和糖酸转化率分别提高了20.1%和15.6%。结果表明,异源表达 CsgapC 有助于提高谷氨酸棒杆菌发酵生产 L -精氨酸和 L -鸟氨酸的水平。展开更多
文摘A novel method for enzymatic synthesis of L-theanine using copper(Ⅱ)-L-glutamine[Cu(Gln)2]as donor substrate was proposed.The structure of Cu(Gln)2 was identified by infrared spectrum analysis and its stability was also investigated under the reaction conditions.The enzymatic synthesis of L-theanine catalyzed by γ-glutamyltranspeptidase was carried out by using Cu(Gln)2 and L-glutamine as donor substrate respectively,and the product yield and conversion rate of donor substrate were compared under the conditions of different ratios of donor and acceptor.The results showed that the transpeptidation reaction could be effectively enhanced by using Cu(Gln)2 as donor substrate.The conversion rate of donor would increase by 51.5%,44.9% and 27.1% under different reaction conditions,compared to that using L-Gln as donor substrate.When the molar ratio of donor to acceptor was 6∶100,a higher donor conversion of 71.3% was obtained.
