The addition of Co2+ enhances the catalytic efficiency and thermostability of recombinant glucose isomerase from Thermobifida fusca |
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Authors: | Fan Zhang Xuguo Duan Sheng Chen Dan Wu Jian Chen Jing Wu |
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Affiliation: | 1. State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, People''s Republic of China;2. School of Biotechnology and Key Laboratory of Industrial Biotechnology Ministry of Education, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, People''s Republic of China |
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Abstract: | Glucose isomerase is an important industrial enzyme that catalyzes the reversible isomerization of glucose to fructose. In this study, the effect of cobalt ions (Co2+) on the catalytic efficiency and thermostability of recombinant glucose isomerase from Thermobifida fusca was analyzed. The activity of glucose isomerase from engineered Escherichia coli supplemented with 1 mM Co2+ (C-GI) reached 41 U/ml, 2.1-fold higher than enzyme prepared from E. coli without additive (GI). The purified C-GI also exhibited an increased specific activity (23.8 U/mg compared to 12.1 U/mg for GI) and a greater thermostability (half-life of 17 h at 75 °C, 11.3-fold higher than GI (1.5 h)). The optimal temperature for C-GI shifted from 80 °C to 85 °C and demonstrated higher activity over pH 7.0–9.0. The kcat/Km value of C-GI (89.3 M?1 s?1) for the isomerization of glucose to fructose was nearly 1.75-fold higher than that of GI. In addition, the engineered cells were immobilized with the method of flocculation-cross linking. The immobilized cells supplemented with 1 mM Co2+ (C-IGI) had a better operational performance than cells without additives (IGI); at the end of 6 cycles, the conversion rate of C-IGI was still 43.1%, meeting the conversion rate requirement. |
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Keywords: | Glucose isomerase Catalytic efficiency Thermostability Immobilization |
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