jo0525682_si_001.pdf (1.64 MB)
Synthesis of a Library of Xylogluco-Oligosaccharides for Active-Site Mapping of Xyloglucan endo-Transglycosylase
journal contribution
posted on 2006-07-07, 00:00 authored by Régis Fauré, Marc Saura-Valls, Harry Brumer, Antoni Planas, Sylvain Cottaz, Hugues DriguezComplex oligosaccharides containing α-d-xylosyl-(1→6)-β-d-glucosyl residues and unsubstituted β-(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 α-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.
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chemical synthesisenzymeSynthesioligosaccharidedegradationcompoundOHyieldunsubstitutedterminal glucosyl unitsfluoridereaction productHumicola insolensdonor synthonenzymaticallyresidueXETplant cell wall biosynthesislactosyl motifefficiencyacceptorgalactosebuilding blockssynthesizingCel 7B E 197A glycosynthasexyloglucan polymersConstitutingsitetarget moleculesMappingmodificationmappingcondensationlactoseXyloglucan
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