- Glucoamylase originating from Schwanniomyces occidentalis is a typical α-glucosidase
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A starch-hydrolyzing enzyme from Schwanniomyces occidentalis has been reported to be a novel glucoamylase, but there is no conclusive proof that it is glucoamylase. An enzyme having the hydrolytic activity toward soluble starch was purified from a strain of S. occidentalis. The enzyme showed high catalytic efficiency (kcat/Km) for maltooligosaccharides, compared with that for soluble starch. The product anomer was α-glucose, differing from glucoamylase as a β-glucose producing enzyme. These findings are striking characteristics of α-glucosidase. The DNA encoding the enzyme was cloned and sequenced. The primary structure deduced from the nucleotide sequence was highly similar to mold, plant, and mammalian α-glucosidases of α-glucosidase family II and other glucoside hydrolase family 31 enzymes, and the two regions involved in the catalytic reaction of α-glucosidases were conserved. These were no similarities to the so-called glucoamylases. It was concluded that the enzyme and also S. occidentalis glucoamylase, had been already reported, were typical α-glucosidases, and not glucoamylase.
- Sato, Fumiaki,Okuyama, Masayuki,Nakai, Hiroyuki,Mori, Haruhide,Kimura, Atsuo,Chiba, Seiya
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Read Online
- Direct Synthesis of para-Nitrophenyl Glycosides from Reducing Sugars in Water
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Reducing sugars may be directly converted into the corresponding para-nitrophenyl (pNP) glycosides using 2-chloro-1,3-dimethylimidazolinium chloride (DMC), para-nitrophenol, and a suitable base in aqueous solution. The reaction is stereoselective for sugars with either a hydroxyl or an acetamido group at position 2, yielding the 1,2-trans pNP glycosides. A judicious choice of base allows extension to di-and oligosaccharide substrates, including a complex N-glycan oligosaccharide isolated from natural sources, without the requirement of any protecting group manipulations
- Fairbanks, Antony J.,Qiu, Xin
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supporting information
(2020/03/24)
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- Substrate and preparation method and application thereof
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The invention discloses a substrate namely alpha-D-glucoside for detecting activity of alpha-glucosidases, and further discloses a synthesis technology of the substrate. The synthesis technology comprises the steps of enabling a compound alpha-D-glucose and acetyl chloride to be subjected to a reaction, and performing purification to obtain alpha-D- pentacetylglucose; catalyzing the obtained substances with N,N-Dimethyl-1,3-diaminopropane, performing pickling, performing extraction, performing drying, and performing purifying to obtain 2,3,4,6-tetra-O-acetyl-alpha-D-acetyl-glucosamine; catalyzing the obtained substances in a dichloromethane solution, performing a reaction with trichloroacetonitrile, performing filtering, and performing purifying to obtain 2,3,4,6-tetra-O-acetyl-beta-D-glucosyl trichloroacetimidate; performing catalyzing on the obtained substances in a dichloromethane solution, performing a reaction with chromogen or fluorophore, performing extraction, merging organic phases, performing drying, performing concentrating, performing methanol redissolution, performing crystal nourishing at 4 DEG C, and performing filtering to obtain 2,3,4,6-tetra-O-acetyl-alpha-D-glucoside; and catalyzing the obtained substances in a methanolic solution, performing a reaction, then performing decoloring adsorption, performing filtering, and performing purifying. The synthesis technology of the substrate is simple and high in yield, the sensitivity of a reagent kit can be improved, the stability is good, and the specificity is high.
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Paragraph 0027; 0028
(2019/05/15)
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- Biphasic catalysis with disaccharide phosphorylases: Chemoenzymatic synthesis of α- D -glucosides using sucrose phosphorylase
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Thanks to its broad acceptor specificity, sucrose phosphorylase (SP) has been exploited for the transfer of glucose to a wide variety of acceptor molecules. Unfortunately, the low affinity (Km > 1 M) of SP towards these acceptors typically urges the addition of cosolvents, which often either fail to dissolve sufficient substrate or progressively give rise to enzyme inhibition and denaturation. In this work, a buffer/ethyl acetate ratio of 5:3 was identified to be the optimal solvent system, allowing the use of SP in biphasic systems. Careful optimization of the reaction conditions enabled the synthesis of a range of α-d-glucosides, such as cinnamyl α-d-glucopyranoside, geranyl α-d-glucopyranoside, 2-O-α-d-glucopyranosyl pyrogallol, and series of alkyl gallyl 4-O-α-d-glucopyranosides. The usefulness of biphasic catalysis was further illustrated by comparing the glucosylation of pyrogallol in a cosolvent and biphasic reaction system. The acceptor yield for the former reached only 17.4%, whereas roughly 60% of the initial pyrogallol was converted when using biphasic catalysis.
- De Winter, Karel,Desmet, Tom,Devlamynck, Tim,Van Renterghem, Lisa,Verhaeghe, Tom,Pelantova, Helena,Kren, Vladimir,Soetaert, Wim
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p. 781 - 787
(2014/07/08)
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- Purification, characterization, and gene identification of an α-glucosyl transfer enzyme, a novel type α-glucosidase from Xanthomonas campestris WU-9701
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The α-glucosyl transfer enzyme (XgtA), a novel type α-glucosidase produced by Xanthomonas campestris WU-9701, was purified from the cell-free extract and characterized. The molecular weight of XgtA is estimated to be 57 kDa by SDS-PAGE and 60 kDa by gel filtration, indicating that XgtA is a monomeric enzyme. Kinetic properties of XgtA were determined for α-glucosyl transfer and maltose-hydrolyzing activities using maltose as the α-glucosyl donor, and if necessary, hydroquinone as the acceptor. The Vmax value for α-glucosyl transfer activity was 1.3 × 10-2 (mM/s); this value was 3.9-fold as much as that for maltose-hydrolyzing activity. XgtA neither produced maltooligosaccharides nor hydrolyzed sucrose. The gene encoding XgtA that contained a 1614-bp open reading frame was cloned, identified, and highly expressed in Escherichia coli JM109 as the host. Site-directed mutagenesis identified Asp201, Glu270, and Asp331 as the catalytic sites of XgtA, indicating that XgtA belongs to the glycoside hydrolase family 13.
- Sato, Toshiyuki,Hasegawa, Nobukazu,Saito, Jun,Umezawa, Satoru,Honda, Yuki,Kino, Kuniki,Kirimura, Kohtaro
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body text
p. 20 - 27
(2012/09/05)
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- Syntheses of p-nitrophenyl 3- and 4-thio-β-d-glycopyranosides
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Thioglycosides have proved to be useful, enzymatically stable analogs of glycosides for structural and mechanistic studies and their synthesis is considerably simplified through the use of thioglycoligases. As part of an investigation into the use of thio
- Chen, Hong-Ming,Withers, Stephen G.
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experimental part
p. 2596 - 2604
(2011/01/12)
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- Sulfatase-catalyzed assembly of regioselectively O-sulfonated p-nitrophenyl α-D-gluco- and α-D-mannopyranosides
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A chemoenzymic methodology is extended to the library synthesis of regioselectively O-sulfonated pNP D-gluco and D-mannopyranosides. The method involves the sequential reactions of chemical O-sulfonation and sulfatase-catalyzed O-desulfonation. pNP 2,6-di-O-sulfo-α-D- glucopyranoside and pNP 3,6-di-O-sulfo-α-D-mannopyranoside were obtained as sodium salts using chemical methods by way of dibutylstannylene acetals or tributylstannyl ethers. They were then applied to enzyme reactions using three molluscan enzymes (snail, limpet, and abalone). The sulfatase reactions cleaved a sulfate group at the secondary O-2 or O-3 position to yield the corresponding pNP 6-O-sulfo sugars. Neither pNP 6-O-sulfo-α-D-glucopyranoside nor 6-O-sulfo-α-D-mannopyranoside became the enzyme substrate. Evidently, the molluscan sulfatases have a tendency to cleave the secondary O-sulfo group with assistance from the 6-O-sulfo group.
- Uzawa, Hirotaka,Nishida, Yoshihiro,Sasaki, Kenji,Nagatsuka, Takehiro,Hiramatsu, Hideo,Kobayashi, Kazukiyo
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p. 1597 - 1602
(2007/10/03)
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- Carbohydrate-carbohydrate interactions in water with glycophanes as model systems
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The synthesis and conformational properties of glycophanes 2 and 3 (cyclodextrin-cyclophane hybrid receptors containing two maltose units linked by (4-hydroxymethyl) benzoic acid spacer) are described. The binding properties in water of these receptors with a series of 4-nitrophenyl glycosides with α- and β-configurations at the anomeric center have been studied using 1H NMR spectroscopy and molecular mechanics calculations. A comparison of these properties with those of glycophane 1 (an α,α-trehalose containing glycophane) and α-cyclodextrin (αCD) using the same glycosides shows the existence of a stabilizing contribution to the free energy of binding in the case of of glycophanes but not in the case of the αCD system. This contribution is due to carbohydrate-carbohydrate interactions between both host and guest lipophilic sugar surfaces. Glycophanes 1, 2, and 3 show similar α/β selectivity on binding the ligands, despite the great flexibility of 3 related to 1 and 2. Parallels are drawn between the thermodynamic behavior of these model systems and that proposed for sugar- protein interactions.
- Morales, Juan Carlos,Zurita, Dacil,Penades, Soledad
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p. 9212 - 9222
(2007/10/03)
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- Subsite mapping of porcine pancreatio alpha-amylase I and II using 4-nitrophenyl-α-maltooligosaccharides
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The catalytic efficiency (kcat/Km) and the cleaved bond distribution for the nitrophenylated maltooligosaccharides, p-NPGIcn (2n7) hydrolysed by porcine pancreatic alpha-amylase isozymes I and II were determined. the subsite affinities (Ai) were calculated from the p-NPGlcn (4n7) hydrolysis data.Five subsites (-3 to 2) bind glucosidic residues with a positive affinity.No additional subsites could be detected both at the reducing end (3,4,5)and at the nonreducing end (-4,-5,-6).The energetic profiles of both isozymes are similar.The energetic profile of PPA differs from other alpha-amylases by having both a small number of subsites, and a catalytic subsite with a high positive affinity.Excellent agreement was found between observed catalytic efficiency values and those calculated from the subsite affinities. Keywords: alpha-Amylase isozymes; Active centre; Subsite structure; Energetic profile; Porcine pencreatic alpha-amylaseKeywords: alpha-Amylase isozymes; Active centre; Subsite structure; Energetic profile; Porcine Pancreatic alpha-amylase
- Ajandouz, El Hassan,Marchis-Mouren, Guy J.
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p. 267 - 278
(2007/10/02)
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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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- 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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