Determining Substrate Specificities of β1,4-Endogalactanases Using Plant Arabinogalactan Oligosaccharides Synthesized by Automated Glycan Assembly
作者:Max P. Bartetzko、Frank Schuhmacher、Peter H. Seeberger、Fabian Pfrengle
DOI:10.1021/acs.joc.6b02745
日期:2017.2.3
glycosyl hydrolases. We report the automatedglycanassembly of oligosaccharides related to the arabinogalactan side chains of pectin as novel biochemical tools to determine the substratespecificities of endogalactanases. Analysis of the digestion products revealed different requirements for the lengths and arabinose substitution pattern of the oligosaccharides to be recognized and hydrolyzed by the
nature of non‐cellulosic polysaccharides, such as arabinoxylan, makes it difficult to correlate molecular structure with macroscopic properties. To study the impact of specific structural features of the polysaccharides on crystallinity or affinity to other cell wall components, collections of polysaccharides with defined repeating units are required. Herein, a chemoenzymaticapproach to artificial
La(OTf)3: An Efficient Promoter for Thioglycoside Activation in Conjunction with N-Iodosuccinimide
作者:Balaram Mukhopadhyay、Somnath Mukherjee
DOI:10.1055/s-0030-1259016
日期:2010.12
Use of La(OTf)3 as a Lewis acid promoter for N-iodosuccinimide-mediated activation of thioglycosides is reported. The glycosylation reactions proceeded smoothly with good to excellent yields and stereoselectivity.
Use of Furanoid Glycals in Oligosaccharide Synthesis
作者:Cornelis Timmers、Jeroen Verheijen、Gijsbert van der Marel、Jacobus van Boom
DOI:10.1055/s-1997-5756
日期:1997.7
Furanoid glycals 3, 4 and 9, containing a 3-O-silyl protecting group, are readily epoxidized with DMD to give the respective shelf-stable α-1,2-anhydrofuranoses 7, 8 and 10. The latter oxiranes react smoothly and stereoselectively under the agency of ZnCl2 with a variety of primary and allylic secondary glycosyl acceptors (e.g. 1, 11-13) resulting in the exclusive formation of β-linked disaccharides (e.g. 14-18) in yields comparable to those obtained starting from 1,2-anhydropyranoses. Furthermore, the dimeric glucofuranoside 18 was transformed into the corresponding 2'-deoxyfuranoside 20, the β-mannofuranoside 21 and the (1→2)-branched furanoside 22.
The spacer-containing tetramericarabinogalactans 1−3, suitable for CCRC-M7 epitope characterization, are readily accessible by ZnCl2-assisted stepwise elongation of 11-methoxycarbonylundecanol 9 with the 1,2-anhydrogalactose building unit 6. NIS/cat. TfOH-mediated glycosylation of the newly formed 2-OH, 2′-OH, or 2′′-OH function in the β-(16)-galactoside backbone with the 1-thioarabinofuranoside donor