2106-10-7Relevant articles and documents
The crystal structure of an inverting glycoside hydrolase family 9 exo-β-D-glucosaminidase and the design of glycosynthase
Honda, Yuji,Arai, Sachiko,Suzuki, Kentaro,Kitaoka, Motomitsu,Fushinobu, Shinya
, p. 463 - 472 (2016)
Exo-β-D-glucosaminidase (EC 3.2.1.165) from Photobacterium profundum (PpGlcNase) is an inverting GH (glycoside hydrolase) belonging to family 9.We have determined the three-dimensional structure of PpGlcNase to describe the first structure-function relationship of an exo-type GH9 glycosidase. PpGlcNase has a narrow and straight active-site pocket, in contrast with the long glycan-binding cleft of a GH9 endoglucanase. This is because PpGlcNase has a long loop, which blocks the position corresponding to subsites -4 to -2 of the endoglucanase. The pocket shape of PpGlcNase explains its substrate preference for a β1,4-linkage at the non-reducing terminus. Asp139, Asp143 and Glu555 in the active site were located near the β-O1 hydroxy group of GlcN (D-glucosamine), with Asp139 and Asp143 holding a nucleophilic water molecule for hydrolysis. The D139A, D143A and E555A mutants significantly decreased hydrolytic activity, indicating their essential role. Of these mutants, D139A exclusively exhibited glycosynthase activity using α-GlcN-F (α-D-glucosaminyl fluoride) and GlcN as substrates, to produce (GlcN)2. Using saturation mutagenesis at Asp139, we obtained D139E as the best glycosynthase. Compared with the wild-type, the hydrolytic activity of D139E was significantly suppressed (--release activity also decreased (3%). Therefore the glycosynthase activity of D139Ewas lower than that of glycosynthases created previously from other inverting GHs. Mutation at the nucleophilic water holder is a general strategy for creating an effective glycosynthase from inverting GHs.However, for GH9, where two acidic residues seem to share the catalytic base role, mutation of Asp139 might inevitably reduce F.-release activity.
THE BEHAVIOR OF CELLULOSE, AMYLOSE, AND β-D-XYLAN TOWARDS ANHYDROUS HYDROGEN FLUORIDE
Defaye, Jacques,Gadelle, Andree
, p. 217 - 228 (1982)
Cellulose, amylose, and D-glucose are converted into α-D-glucopyranosyl fluoride (3) when dissolved in anhydrous hydrogen fluoride.The fluoride subsequently undergoes condensation to afford a mixture of oligosaccharides, probably via an oxocarbonium ion.The fluoride 3 and the oligosaccharides are in equilibrium, which was studied by 13C-n.m.r. spestroscopy; in dilute solution in hydrogen fluoride, the D-glucosyl fluoride is the main product present, but when the hydrogen fluoride is evaporated, the equilibrium is shifted towards the oligosaccharides.These costitute a complex mixture which was studied by methylation and subsequent analysis of the methylated alditols derived therefrom. (1-->4)-β-D-Xylan and D-xylose behave similarly to the D-glucose derivatives towards hydrogen fluoride.
Selective C?O Bond Cleavage of Sugars with Hydrosilanes Catalyzed by Piers’ Borane Generated In Situ
Zhang, Jianbo,Park, Sehoon,Chang, Sukbok
supporting information, p. 13757 - 13761 (2017/10/09)
Described herein is the selective reduction of sugars with hydrosilanes catalyzed by using Piers’ borane [(C6F5)2BH] generated in situ. The hydrosilylative C?O bond cleavage of silyl-protected mono- and disaccharides in the presence of a (C6F5)2BH catalyst, generated in situ from (C6F5)2BOH, takes place with excellent chemo- and regioselectivities to provide a range of polyols. A study of the substituent effects of sugars on the catalytic activity and selectivity revealed that the steric environment around the anomeric carbon (C1) is crucial.
Aqueous Glycosylation of Unprotected Sucrose Employing Glycosyl Fluorides in the Presence of Calcium Ion and Trimethylamine
Pelletier, Guillaume,Zwicker, Aaron,Allen, C. Liana,Schepartz, Alanna,Miller, Scott J.
supporting information, p. 3175 - 3182 (2016/03/19)
We report a synthetic glycosylation reaction between sucrosyl acceptors and glycosyl fluoride donors to yield the derived trisaccharides. This reaction proceeds at room temperature in an aqueous solvent mixture. Calcium salts and a tertiary amine base promote the reaction with high site-selectivity for either the 3′-position or 1′-position of the fructofuranoside unit. Because nonenzymatic aqueous oligosaccharide syntheses are underdeveloped, mechanistic studies were carried out in order to identify the origin of the selectivity, which we hypothesized was related to the structure of the hydroxyl group array in sucrose. The solution conformation of various monodeoxysucrose analogs revealed the co-operative nature of the hydroxyl groups in mediating both this aqueous glycosyl bond-forming reaction and the site-selectivity at the same time.
Glycosynthases from Thermotoga neapolitana β-glucosidase 1A: A comparison of α-glucosyl fluoride and in situ-generated α-glycosyl formate donors
Pozzo, Tania,Plaza, Merichel,Romero-Garcia, Javier,Faijes, Magda,Karlsson, Eva Nordberg,Planas, Antoni
, p. 132 - 139 (2014/07/21)
TnBgl1A from the thermophile Thermotoga neapolitana is a dimeric β-glucosidase that belongs to glycoside hydrolase family 1 (GH1), with hydrolytic activity through the retaining mechanism, and a broad substrate specificity acting on β-1,4-, β-1,3- and β-1,6-linkages over a range of glyco-oligosaccharides. Three variants of the enzyme (TnBgl1A-E349G, TnBgl1A-E349A and TnBgl1A-E349S), mutated at the catalytic nucleophile, were constructed to evaluate their glycosynthase activity towards oligosaccharide synthesis. Two approaches were used for the synthesis reactions, both of which utilized 4-nitrophenyl β-d-glucopyranoside (4NPGlc) as an acceptor molecule: the first using an α-glucosyl fluoride donor at low temperature (35 °C) in a classical glycosynthase reaction, and the second by in situ generation of the glycosyl donor with (4NPGlc), where formate served as the exogenous nucleophile under higher temperature (70 °C). Using the first approach, TnBgl1A-E349G and TnBgl1A-E349A synthesized disaccharides with β-1,3-linkages in good yields (up to 61%) after long incubations (15 h). However, the GH1 glycosynthase Bgl3-E383A from a mesophilic Streptomyces sp., used as reference enzyme, generated a higher yield at the same temperature with both a shorter reaction time and a lower enzyme concentration. The second approach yielded disaccharides for all three mutants with predominantly β-1,3-linkages (up to 45%) but also β-1,4-linkages (up to 12.5%), after 7 h reaction time. The TnBgl1A glycosynthases were also used for glycosylation of flavonoids, using the two described approaches. Quercetin-3-glycoside was tested as an acceptor molecule and the resultant product was quercetin-3,4′-diglycosides in significantly lower yields, indicating that TnBgl1A preferentially selects 4NPGlc as the acceptor.
Glycosynthase with broad substrate specificity-an efficient biocatalyst for the construction of oligosaccharide library
Wei, Jinhua,Lv, Xun,Lue, Yang,Yang, Gangzhu,Fu, Lifeng,Yang, Liu,Wang, Jianjun,Gao, Jianhui,Cheng, Shuihong,Duan, Qian,Jin, Cheng,Li, Xuebing
supporting information, p. 2414 - 2419 (2013/05/23)
A versatile glycosynthase (TnG-E338A) with strikingly broad substrate scope has been developed from Thermus nonproteolyticus β-glycosidase (TnG) by using site-directed mutagenesis. The practical utility of this biocatalyst has been demonstrated by the facile generation of a small library containing various oligosaccharides and a steroidal glycoside (total 25 compounds) in up to 100 % isolated yield. Moreover, an array of eight gluco-oligosaccharides has been readily synthesized by the enzyme in a one-pot, parallel reaction, which highlights its potential in the combinatorial construction of a carbohydrate library that will assist glycomic and glycotherapeutic research. Significantly, the enzyme provides a means by which glycosynthase technology may be extended to combinatorial chemistry.
Creation of an α-mannosynthase from a broad glycosidase scaffold
Yamamoto, Keisuke,Davis, Benjamin G.
supporting information; experimental part, p. 7449 - 7453 (2012/09/21)
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
Formation of homooligosaccharides using base-promoted glycosylation of unprotected glycosyl fluorides
Steinmann, Andreas,Thimm, Julian,Matwiejuk, Martin,Thiem, Joachim
experimental part, p. 3606 - 3612 (2011/10/12)
Homooligomeric saccharides are of general interest with potential applications in chemical, pharmaceutical, and food industry as well as for materials with novel properties. This contribution describes a methodology of a base-promoted "single step self-oligomerization" of glycosyl fluorides as donors leading to oligomers with up to ～25 saccharide units. The influences of base and reaction time were examined. Linkage analysis of the corresponding alditol acetates by GC/MS allowed for calculation of average structural elements of oligomers.
Escherichia coli glucuronylsynthase: An engineered enzyme for the synthesis of β-glucuronides
Wilkinson, Shane M.,Liew, Chu W.,Mackay, Joel P.,Salleh, Hamzah M.,Withers, Stephen G.,McLeod, Malcolm D.
supporting information; experimental part, p. 1585 - 1588 (2009/04/10)
The glycosynthase derived from E. coli β-glucuronidase catalyzes the glucuronylation of a range of primary, secondary, and aryl alcohols with moderate to excellent yields. The procedure provides an efficient, stereoselective, and scalable single-step synthesis of β-glucuronides under mild conditions.
A glycosynthase catalyst for the synthesis of flavonoid glycosides
Yang, Min,Davies, Gideon J.,Davis, Benjamin G.
, p. 3885 - 3888 (2008/02/14)
Mutant exposed! The synthetic utility of glycosynthase mutant enzymes has been expanded to allow the use of lipophilic acceptors, such as flavonoids, at rates comparable with those of natural glycosyltransferases. Sequential biocatalysis allows access to both di- and monosaccharide-modifled products as well as natural product glycoflavonoids. (Figure Presented).
