Purification and characterization of a highly selective sucrose isomerase from Erwinia rhapontici NX-5 |
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Authors: | Ben Ren Sha Li Hong Xu Xiao-hai Feng Heng Cai Qi Ye |
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Institution: | (1) State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing University of Technology, No. 5 New Model Road, Nanjing, 210009, Jiangsu, People’s Republic of China;(2) National Engineering Technique Research Center for Biotechnology, Nanjing, 211816, People’s Republic of China; |
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Abstract: | A highly selective sucrose isomerase (SIase) was purified to homogeneity from the cell-free extract of Erwinia rhapontici NX-5 with a recovery of 27.7% and a fold purification of 213.6. The purified SIase showed a high specific activity of 427.1 U mg−1 with molecular weight of 65.6 kDa. The K
m for sucrose was 222 mM while V
max was 546 U mg−1. The optimum pH and temperature for SIase activity were 6.0 and 30 °C, respectively. The purified SIase was stable in the
temperature range of 10–40 °C and retained 65% of the enzyme activity after 2 weeks’ storage at 30 °C. The SIase activity
was enhanced by Mg2+ and Mn2+, inhibited by Ca2+, Cu2+, Zn2+, and Co2+, completely inhibited by Hg2+ and Ag2+. The purified SIase was strongly inhibited by SDS, while partially inhibited by dimethylformamide, tetrahydrofuran, and PMSF.
Additionally, glucose and fructose acted as competitive inhibitors for purified SIase. |
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