- Heterologous expression of a thermostable α-glucosidase from Geobacillus sp. Strain HTA-462 by Escherichia coli and its potential application for isomaltose–oligosaccharide synthesis
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Isomaltose–oligosaccharides (IMOs), as food ingredients with prebiotic functionality, can be prepared via enzymatic synthesis using α-glucosidase. In the present study, the α-glucosidase (GSJ) from Geobacillus sp. strain HTA-462 was cloned and expressed in Escherichia coli BL21 (DE3). Recombinant GSJ was purified and biochemically characterized. The optimum temperature condition of the recombinant enzyme was 65 ?C, and the half-life was 84 h at 60 ?C, whereas the enzyme was active over the range of pH 6.0–10.0 with maximal activity at pH 7.0. The α-glucosidase activity in shake flasks reached 107.9 U/mL and using 4-Nitrophenyl β-D-glucopyranoside (pNPG) as substrate, the Km and Vmax values were 2.321 mM and 306.3 U/mg, respectively. The divalent ions Mn2+ and Ca2+ could improve GSJ activity by 32.1% and 13.8%. Moreover, the hydrolysis ability of recombinant α-glucosidase was almost the same as that of the commercial α-glucosidase (Bacillus stearothermophilus). In terms of the transglycosylation reaction, with 30% maltose syrup under the condition of 60 ?C and pH 7.0, IMOs were synthesized with a conversion rate of 37%. These studies lay the basis for the industrial application of recombinant α-glucosidase.
- Zhang, Fan,Wang, Weiyang,Bah, Fatoumata Binta Maci,Song, Chengcheng,Zhou, Yifa,Ji, Li,Yuan, Ye
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- Heterologous expression and biochemical characterization of α-glucosidase from aspergillus niger by pichia pastroris
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The aglu of Aspergillus niger encodes the pro-protein of α-glucosidase, and the mature form of wild-type enzyme is a heterosubunit protein. In the present study, the cDNA of α-glucosidase was cloned and expressed in Pichia pastoris strain KM71. The activity of recombinant enzyme in a 3 L fermentor reached 2.07 U/mL after 96 h of induction. The recombinant α-glucosidase was able to produce oligoisomaltose. The molecular weight of the recombinant enzyme was estimated to be about 145 kDa by SDS-PAGE, and it reduced to 106 kDa after deglycosylation. The enzymatic activity of recombinant α-glucosidase was not significantly affected by a range of metal ions. The optimum temperature of the enzyme was 60 °C, and it was stable below 50 °C. The enzyme was active over the range of pH 3.0-7.0 with maximal activity at pH 4.5. Using pNPG as substrate, the Km and Vmax values were 0.446 mM and 43.48 U/mg, respectively. These studies provided the basis for the application of recombinant α-glucosidase in the industry of functional oligosaccharides.
- Chen, Dong-Li,Tong, Xing,Chen, Shang-Wei,Chen, Sheng,Wu, Dan,Fang, Shu-Guang,Wu, Jing,Chen, Jian
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experimental part
p. 4819 - 4824
(2011/08/03)
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- Branched alpha-glucan, alpha-glucosyltransferase which forms the glucan, their preparation and uses
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The present invention has objects to provide a glucan useful as water-soluble dietary fiber, its preparation and uses. The present invention solves the above objects by providing a branched α-glucan, which is constructed by glucose molecules and characterized by methylation analysis as follows: (1) Ratio of 2,3,6-trimethyl-1,4,5-triacetyl-glucitol to 2,3,4-trimethyl-1,5,6-triacetyl-glucitol is in the range of 1:0.6 to 1:4;(2) Total content of 2,3,6-trimethyl-1,4,5-triacetyl-glucitol and 2,3,4-trimethyl-1,5,6-triacetyl-glucitol is 60% or higher in the partially methylated glucitol acetates;(3) Content of 2,4,6-trimethyl-1,3,5-triacetyl-glucitol is 0.5% or higher but less than 10% in the partially methylated glucitol acetates; and(4) Content of 2,4-dimethyl-1,3,5,6-tetraacetyl-glucitol is 0.5% or higher in the partially methylated glucitol acetates; a novel α-glucosyltransferase which forms the branched α-glucan, processes for producing them, and their uses.
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Page/Page column 18-19
(2010/06/11)
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- Research on the strong transglycosylation activity in Aspergillus niger
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Aspergillus niger M-1 strain shows strong transglycosylation activity. A gene of it was introduced into Escherichia coli, and isomalto-oligosaccharides were isolated by a chemical enzymatic method in order to measure the transglycosylation activity.
- Yu, Lan,Zhang, Yun-Kai,Qin, Yong-Ling,Liu, Yu-Yan,Liang, Zhi-Qun
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experimental part
p. 749 - 751
(2009/05/09)
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