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Synthesis of a library of xylogluco-oligosaccharides for active-site mapping of xyloglucan endo-transglycosylase

TitleSynthesis of a library of xylogluco-oligosaccharides for active-site mapping of xyloglucan endo-transglycosylase
Publication TypeJournal Article
Year of Publication2006
AuthorsFaure, R, Saura-Valls, M, Brumer, H, Planas, A, Cottaz, S, Driguez, H
JournalJOURNAL OF ORGANIC CHEMISTRY
Volume71
Pagination5151-5161
Date PublishedJUL 7
Type of ArticleArticle
ISSN0022-3263
Abstract

{[}GRAPHICS] Complex oligosaccharides containing R-D-xylosyl-(1 -> 6)-beta-D-glucosyl residues and unsubstituted beta-(1 -> 4)-linked D-glucosyl units were readily synthesized using enzymatic coupling catalyzed by the Cel7B E197A glycosynthase from Humicola insolens. Constituting this library required four key steps: ( 1) preparing unprotected building blocks by chemical synthesis or enzymatic degradation of xyloglucan polymers; (2) generating the donor synthon in the enzymatic coupling by temporarily introducing a lactosyl motif on the 4-OH of the terminal glucosyl units of the xylogluco-oligosaccharides; ( 3) synthesizing the corresponding R-fluorides, followed by their de-O-acetylation and the glycosynthase-catalyzed condensation of these donors onto various acceptors; and (4) enzymatically releasing lactose or galactose from the reaction product, affording the target molecules in good overall yields. These complex oligosaccharides proved useful for mapping the active site of a key enzyme in plant cell wall biosynthesis and modification: the xyloglucan endo-transglycosylase (XET). We also report some preliminary enzymatic results regarding the efficiency of these compounds.

DOI10.1021/jo0525682