A versatile glycosynthase (TnG-E338A) with strikingly broadsubstrate 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
The Role of Sugar Substituents in Glycoside Hydrolysis
作者:Mark N. Namchuk、John D. McCarter、Adam Becalski、Trevor Andrews、Stephen G. Withers
DOI:10.1021/ja992044h
日期:2000.2.1
used to probe the mechanism of spontaneous β-glycoside hydrolysis. Their relative rates of hydrolysis followed the order 2-deoxy > 4-deoxy > 3-deoxy ≈ 6-deoxy > parent > 6-deoxy-6-fluoro > 3-deoxy-3-fluoro > 4-deoxy-4-fluoro > 2-deoxy-2-fluoro. Hammett correlations of the pH-independent hydrolysis rates of each of the 6-, 4-, 3-, and 2-position substituted glycosides with the σI value for the sugar
Synthesis of Altrose Poly-amido-saccharides with β-<i>N</i>-(1→2)-<scp>d</scp>-amide Linkages: A Right-Handed Helical Conformation Engineered in at the Monomer Level
作者:Ruiqing Xiao、Eric L. Dane、Jialiu Zeng、Christopher J. McKnight、Mark W. Grinstaff
DOI:10.1021/jacs.7b07405
日期:2017.10.11
of amide-linked saccharide oligomers and polymers, which are predisposed to fold into specific ordered secondarystructures, is of significant interest. Herein, right-handed helical poly amido-saccharides (PASs) with β-N-(1→2)-d-amide linkages are synthesized by the anionic ring-opening polymerization of an altrose β-lactam monomer (alt-lactam). The right-handed helical conformation is engineered into
易于折叠成特定有序二级结构的酰胺连接的糖低聚物和聚合物的设计和合成引起了人们的极大兴趣。这里,右手螺旋的聚酰氨基-糖(PASS)与β- ñ - (1→2) - d -酰胺键是通过阿卓糖β-内酰胺单体(ALT-内酰胺)的阴离子开环聚合来合成。通过三氯乙酰基异氰酸酯与具有3-苄氧基的D-糖基的立体定向[2 + 2]环加成,在单体中预装内酰胺环的β构型,将右旋螺旋构象工程化到聚合物中。吡喃糖的脸。该叔丁基内酰胺引发的丁基丁基氯的聚合反应顺利进行,得到具有窄分散性的立构规整聚合物。苄基化的聚合物的桦木还原以高收率得到水溶性的altrose PAS(alt-PASs),而不会降解聚合物主链。圆二色性分析表明,alt-PAS在水溶液中采用右旋螺旋构象。此二级构象可在各种不同条件下保持稳定,例如pH(2.0至12.0),温度(5至75°C),离子盐(2.0 M LiCl,NaCl和KCl)以及在存在下蛋白变性剂(4
Selective demethylation of <i>O</i>-aryl glycosides by iridium-catalyzed hydrosilylation
作者:Caleb A. H. Jones、Nathan D. Schley
DOI:10.1039/d1cc00496d
日期:——
The cleavage of alkyl ethers by hydrosilylation is a powerful synthetic tool for the generation of silyl ethers. Previous attempts to apply this transformation to carbohydrate derivatives have been constrained by poor selectivity and preferential reduction of the anomeric position. O-Aryl glycosides are found to be stable under iridium- and borane-catalyzed hydrosilylation conditions, allowing for
performed using a psicofuranosyl acceptor with 1,3,4,6-tetra-O-benzoyl groups. This is the first report on the synthesis of non-reducing disaccharides comprising only rare d-sugars by IAD using protected ketose as a unique acceptor; additionally, this approach is expected to be applicable to the synthesis of functional sweeteners.