- Environmentally benign glycosylation of aryl pyranosides and aryl/alkyl furanosides demonstrating the versatility of thermostable CGTase from Thermoanaerobacterium sp.
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An extensive study on the specificity of transglycosylation and disproportionation of Thermoanaerobacterium sp. cyclodextrin glucosyltransferases against aryl glucopyranosides or furanosides is reported. While a mixture of maltoside and isomaltoside was obtained respectively using p-nitrophenyl glucopyranoside as an acceptor, only one regioisomer, namely p-nitrophenyl α-d-Glcp-(1,3)-α-l-Araf, was isolated using p-nitrophenyl arabinofuranoside as an acceptor. Interestingly, similar outcomes were found when using p-nitrophenyl galactofuranoside. Furthermore, activation by microwave irradiation resulted in faster reaction times and higher yields and led to glucosidic oligosaccharides with up to 70% conversion. The influence of the anomeric and C-4 configurations of the glycosidic acceptors on the transglycosylation, previously stated for the CGTase family, was not observed and unconventional substrate specificity towards alkyl furanosides was highlighted. This journal is the Partner Organisations 2014.
- Pennec, Alize,Legentil, Laurent,Herrera-Estrella, Luis,Ferrieres, Vincent,Chauvin, Anne-Laure,Nugier-Chauvin, Caroline
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- SYNTHETIC CATALYSTS FOR CARBOHYDRATE PROCESSING
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The disclosure relates to molecularly-imprinted cross-linked micelles that can selectively hydrolyze carbohydrates.
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- Acceptor-induced modification of regioselectivity in CGTase-catalyzed glycosylations of p-nitrophenyl-glucopyranosides
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Cyclodextrin glycosyltransferases (CGTase) are reported to selectively catalyze α(1→4)-glycosyl transfer reactions besides showing low hydrolytic activity. Here, the effect of the anomeric configuration of the glycosyl acceptor on the regioselectivity of
- Strompen, Simon,Miranda-Molina, Alfonso,López-Munguía, Agustín,Castillo, Edmundo,Saab-Rincón, Gloria
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- Creation of an α-mannosynthase from a broad glycosidase scaffold
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α-Mannosides made easy: Mutation of a family-GH31 α-glucosidase that displays plasticity to alterations at the 2-OH position of donor substrates created an efficient α-mannoside-synthesizing biocatalyst. A simple fluoride donor reagent was used for the synthesis of a range of mono-α-mannosylated conjugates using the α-mannosynthase displaying low (unwanted) oligomerization activity. Copyright
- Yamamoto, Keisuke,Davis, Benjamin G.
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p. 7449 - 7453
(2012/09/21)
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- Isolation and characterization of a novel α-glucosidase with transglycosylation activity from Arthrobacter sp. DL001
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A strain of Arthrobacter sp. DL001 with high transglycosylation activity was successfully isolated from the Yellow Sea of China. To purify the extracellular enzyme responsible for transglycosylation, a four-step protocol was adopted and the enzyme with electrophoretical purity was obtained. The purified enzyme has a molecular mass of 210 kDa and displays a narrow hydrolysis specificity towards α-1,4-glucosidic bond. Its hydrolytic activity was identified as decreasing in the order of maltotriose > panose > maltose. Only 3.61% maltose activity occurs when p-nitrophenyl α-d-glycopyranoside serves as a substrate, suggesting that this enzyme belongs to the type II α-glucosidase. In addition, the enzyme was able to transfer glucosyl groups from the donors containing α-1,4-glucosidic bond specific to glucosides, xylosides and alkyl alcohols in α-1,4- or α-1,6-manners. A decreased order of activity was observed when maltose, maltotriose, panose, β-cyclodextrin and soluble starch served as glycosyl donors, respectively. When maltose was utilized as a donor and a series of p-nitrophenyl-glycosides as acceptors, the glucosidase was capable of transferring glucosyl groups to p-nitrophenyl-glucosides and p-nitrophenyl-xylosides in α-1,4- or α-1,6-manners. The yields of p-nitrophenyl-oligosaccharides could reach 42-60% in 2 h. When a series of alkyl alcohols were utilized as acceptors, the enzyme exhibited its transglycosylation activities not only to the primary alcohols but also to the secondary alcohols with carbon chain length 1-4. Therefore, all the results indicated that the purified α-glucosidase present a useful tool for the biosynthesis of oligosaccharides and alkyl glucosides.
- Zhou, Kun,Luan, Hong-Wei,Hu, Ying,Ge, Guang-Bo,Liu, Xing-Bao,Ma, Xiao-Chi,Hou, Jie,Wang, Xiu-Li,Yang, Ling
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experimental part
p. 48 - 57
(2012/09/07)
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- α-Glucosidase mutant catalyzes "α-glycosynthase"-type reaction
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Replacement of the catalytic nucleophile Asp481 by glycine in Schizosaccharomyces pombe α-glucosidase eliminated the hydrolytic activity. The mutant enzyme (D481G) was found to catalyze the formation of an α-glucosidic linkage from β-glucosyl fluoride and
- Okuyama, Masayuki,Mori, Haruhide,Watanabe, Kotomi,Kimura, Atsuo,Chiba, Seiya
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p. 928 - 933
(2007/10/03)
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- Examination of the active sites of human salivary α-amylase (HSA)
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The action pattern of human salivary amylase (HSA) was examined by utilising as model substrates 2-chloro-4-nitrophenyl (CNP) β-glycosides of maltooligosaccharides of dp 4-8 and some 4-nitrophenyl (NP) derivatives modified at the nonreducing end with a 4,6-O-benzylidene (Bnl) group. The product pattern and cleavage frequency were investigated by product analysis using HPLC. The results revealed that the binding region in HSA is longer than five subsites usually considered in the literature and suggested the presence of at least six subsites; four glycone binding sites (-4, -3, -2, -1) and two aglycone binding sites (+1, +2). In the ideal arrangement, the six subsites are filled by a glucosyl unit and the release of maltotetraose (G4) from the nonreducing end is dominant. The benzylidene group was also recognisable by subsites (-3) and (-4). The binding modes of the benzylidene derivatives indicated a favourable interaction between the Bnl group and subsite (-3) and an unfavourable one with subsite (-4). Thus, subsite (-4) must be more hydrophylic than hydrophobic. As compared with the action of porcine pancreatic α-amylase (PPA) on the same substrates, the results showed differences in the three-dimensional structure of active sites of HSA and PPA. (C) 2000 Elsevier Science Ltd.
- Kandra, Lili,Gyemant, Gyoengyi
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p. 579 - 585
(2007/10/03)
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- The action of germinated barley alpha-amylases on linear maltodextrins
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The actions of barley alpha-amylase isozymes 1 and 2 (EC 3.2.1.1) on malto-oligosaccharides and their p-nitrophenyl glycosides were similar, but not identical.For each isozyme, transglycosylation occurred with small substrates that were hydrolysed with difficulty, whereas the rates of hydrolysis increased with increase in the size of the substrate for both the malto-oligosaccharides and the p-nitrophenyl glycosides.A p-nitrophenyl group was found to mimic a glucose residue to a large extent.The differences in action of the isozymes are believed to be caused by differences at more than one subsite of the active site.Alysine-arginine substitution is postulated to account for some of the observed variations.
- MacGregor, Alex. W.,Morgan, Joan E.,MacGregor, E. Ann
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p. 301 - 314
(2007/10/02)
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- Galactosylation and glucosylation by use of β-galactosidase
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The transglucosylation activity of β-galactosidase derived from Aspergillus oryzae and Escherichia coli, respectively, was examined in reaction systems containing up to 50% acetonitrile. Starting with ortho-nitrophenyl β-galactoside (1), which functions both as donor and as acceptor, β-Gal(1-6)β-Gal-PhNO2-o (2) and β-Gal(1-3)β-Gal-PhNO2-o (3) were obtained. Under similar conditions the enzyme from A. oryzae converts para-nitrophenyl β-glucoside (5) to β-Glc(1-2)β-Glc-PhNO2-p (6) and α-Glc(1-4)β-Glc-PhNO2-p (7). Incubation of 1 and L-serine in the presence of the A. oryzae β-galactosidase leads to β-Gal-L-Ser (4).
- Sauerbrei,Thiem
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p. 201 - 204
(2007/10/02)
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- A Novel Approach to the Determination of Trace α-Amylase by Photographic Assay. The Synthesis and Enzymatic Characterization of an Oligosaccharide Derivative as a Substrate for α-Amylase from Porcine Pancreas
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In line with a new concept for the photographic assay on the basis of chemical amplification by the catalytic Ag* nuclei, an α-amylase substrate containing a new sensitive labeling component and a bioaffinity group was designed and synthesized.The analysis of enzymatic degradation proved that the substrate can release efficiently the labeling component without loss of photographic activity.
- Ono, Mitsunori,Suzuki, Nobuo,Hirano, Shigeo,Itoh, Isamu,Masuta, Nobuhito
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p. 395 - 398
(2007/10/02)
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- Synthesis of p-nitrophenyl 6(5)-O-benzyl-alpha-maltopentaoside, a substrate for alpha amylases.
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p-Nitrophenyl alpha-maltopentaoside, having a benzyl group on O-6 of the terminal (nonreducing) D-glucosyl group was prepared by use of a reductive ring-opening reaction. Highly regioselective reduction of p-nitrophenyl O-(2,3-di-O-benzoyl-4,6-O-benzylidene-alpha-D-glucopyranosyl)-(1----4)- tris[O-(2,3,6-tri-O-benzoyl-alpha-D-glucopyranosyl)-(1----4)]-2,3,6-tri- O- benzoyl-alpha-D-glucopyranoside by dimethylamine-borane and p-toluenesulfonic acid, followed by debenzoylation, gave p-nitrophenyl O-(6-O-benzyl-alpha-D-glucopyranosyl)-(1----4)-tris[O-alpha-D-glucopyran osyl- (1----4)]-alpha-D-glucopyranoside. An experiment was done on the mode of action of human pancreatic and salivary alpha amylases on this derivative. The compound is suitable as a substrate for the assay of alpha amylase when used with glucoamylase and alpha-D-glucosidase as coupling enzymes.
- Satomura,Iwata,Sakata,Omichi,Ikenaka
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p. 107 - 115
(2007/10/02)
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- STEREOSELECTIVE SYNTHESES OF O- AND S-NITROPHENYL GLYCOSIDES. PART III. SYNTHESES IN THE &α-D-GALACTOPYRANOSE AND &α-MALTOSE SERIES
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The action of p-nitrophenol penta-O-acetyl-β-D-galactopyranose in dichloromethane, in the presence of stannic tetrachloride gave p-nitrophenyl α-D-galactoside in fair yield.This technique failed when o-nitrophenol was used.Tetra-O-acetyl-β-D-galactopyranosyl and hepta-O-acetyl-β-maltosyl chlorides were converted to p- or o-nitrophenyl α-D-glycosides and p-nitrophenyl α-D-1-thioglycosides in good yield using hexamethylphosphoramide as a solvent and the sodium salt of the phenols as nucleophiles.The galactosides have been functionalized for further condensation at the C-4 position by selective benzoylation.
- Apparu, Maecel,Blanc-Muesser, Michele,Defaye, Jacques,Driguez, Hugues
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p. 314 - 320
(2007/10/02)
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