A series of N-bromoacetylglycosylamines and bromoketone C-glycosides were synthesised from complex xyloglucan oligosaccharide (XyGO) scaffolds as specific active-site affinity labels for endo-xyloglucanases. Compounds based on XXXG (Xyl3 Glc4 ) and XLLG (Xyl3 Glc4 Gal2 ) oligosaccharides exhibited strikingly higher affinities and higher rates of irreversible inhibition than known cellobiosyl and new lactosyl disaccharide congeners when tested with endo-xyloglucanases from two distinct glycoside hydrolase (GH) families. Intact-protein mass spectrometry indicated that inactivation with XyGO derivatives generally resulted in a 1:1 labelling stoichiometry. Together, these results indicate that XyGO-based affinity reagents have significant potential as inhibitors and proteomic reagents for the identification and analysis of diverse xyloglucan-active enzymes in nature, to facilitate industrial enzyme applications.
Keywords: carbohydrates; enzymes; glycosyl hydrolases; inhibitors; xyloglucanases.
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