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.
Enzymatic synthesis of carbon-fluorine bonds [8]
Zechel,Reid,Nashiru,Mayer,Stoll,Jakeman,Warren,Withers
, p. 4350 - 4351 (2001)
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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.
, 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.
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
, 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.