- Development of a multiphase reaction system for integrated synthesis of isomaltose with a new glucosyltransferase variant
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A new genetically derived variant of the glucosyltransferase from Streptococcus oralis has been characterized physicochemically and kinetically. Compared with the industrially used glucosyltransferase from Leuconostoc mesenteroides, the enzyme variant GTF-R S628D possesses 25 times higher affinity for the specific glucosylation of glucose. For a concept of integrated reaction and product isolation, a fluidized bed reactor with in situ product removal was applied. The technical feasibility and the applicability of the kinetic models for reaction and adsorption could be demonstrated. The immobilized enzyme was stable (20% activity loss after 192 h) and product could be obtained with 90% purity. A bioprocess model was generated which allowed the integral assessment of the enzymatic synthesis and in situ product adsorption. The model is a powerful tool which assists with the localization of optimal process parameters. It was applied for the process evaluation of other glucosyltransferases and demonstrated key characteristics of each enzymatic system.
- Erhardt, Frank A.,Rosenstock, Philip,Hellmuth, Hendrik,Joerdening, Hans-Joachim
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- 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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- Bioengineering of Leuconostoc mesenteroides glucansucrases that gives selected bond formation for glucan synthesis and/or acceptor-product synthesis
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The variations in glucosidic linkage specificity observed in products of different glucansucrases appear to be based on relatively small differences in amino acid sequences in their sugar-binding acceptor subsites. Various amino acid mutations near active sites of DSRBCB4 dextransucrase from Leuconostoc mesenteroides B-1299CB4 were constructed. A triple amino acid mutation (S642N/E643N/V644S) immediately next to the catalytic D641 (putative transition state stabilizing residue) converted DSRBCB4 enzyme from the synthesis of mainly α-(1→6) dextran to the synthesis of α-(1→6) glucan containing branches of α-(1→3) and α-(1→4) glucosidic linkages. The subsequent introduction of mutation V532P/V535I, located next to the catalytic D530 (nucleophile), resulted in the synthesis of an α-glucan containing increased branched α-(1→4) glucosidic linkages (approximately 11%). The results indicate that mutagenesis can guide glucansucrase toward the synthesis of various oligosaccharides or novel polysaccharides with completely altered linkages without compromising high transglycosylation activity and efficiency.
- Kang, Hee Kyoung,Kimura, Atsuo,Kim, Doman
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p. 4148 - 4155
(2011/10/30)
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- Transglycosylation properties of maltodextrin glucosidase (MalZ) from Escherichia coli and its application for synthesis of a nigerose-containing oligosaccharide
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The transglycosylation reaction of maltodextrin glucosidase (MalZ) cloned and purified from Escherichia coli K12 was characterized and applied to the synthesis of branched oligosaccharides. Purified MalZ preferentially catalyzed the hydrolysis of maltodextrin, γ-cyclodextrin (CD), and cycloamylose (CA). In addition, when the enzyme was incubated with 5% maltotriose (G3), a series of transfer products were produced. The resulting major transfer products, annotated as T1, T2, and T3, were purified and their structures were determined by TLC, MALDI-TOF/MS, 13C NMR, and enzymatic analysis. T1 was identified as a novel compound, maltosyl α-1,3-maltose, whereas T2 and T3 were determined to be isopanose and maltosyl-α-1,6-maltose, respectively. These results indicated that MalZ transferred sugar moiety mainly to C-3 or C-6-OH of glucose of the acceptor molecule. To obtain highly concentrated transfer products, the enzyme was reacted with 10% liquefied cornstarch, and then glucose and maltose were removed by immobilized yeast. The T1 content of the resulting reaction mixture reached 9.0%. The mixture of T1 containing a nigerose moiety can have an immunopotentiating effect on the human body and may be a potential functional sugar stuff.
- Song, Kyung-Mo,Shim, Jae-Hoon,Park, Jong-Tae,Kim, Sung-Hee,Kim, Young-Wan,Boos, Winfried,Park, Kwan-Hwa
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experimental part
p. 87 - 92
(2011/10/18)
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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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- PROCESSES FOR PRODUCING ISOMALTOSE AND ISOMALTITOL AND USE THEREOF
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The present invention aims to provide a novel process for producing isomaltose and isomaltitol, and uses thereof, and it solves the object by establishing a process for producing isomaltose comprising a step of contacting a saccharide, having the α-1,4 glucosidic linkage as the linkage of non-reducing end and a glucose polymerization degree of at least two, with an α-isomaltosyl-transferring enzyme and an α-isomaltosylglucosaccharide-forming enzyme derived from a specific microorganism; a process for producing isomaltitol using the isomaltose produced by the above process; saccharide compositions comprising the isomaltose and/or the isomaltitol produced by the above processes; and uses thereof.
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