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Publication Abstract from PubMed

Small molecule irreversible inhibitors are valuable tools for determining catalytically important active-site residues and revealing key details of the specificity, structure, and function of glycoside hydrolases (GHs). beta-glucans that contain backbone beta(1,3) linkages are widespread in nature, e.g., mixed-linkage beta(1,3)/beta(1,4)-glucans in the cell walls of higher plants and beta(1,3)glucans in yeasts and algae. Commensurate with this ubiquity, a large diversity of mixed-linkage endoglucanases (MLGases, EC 3.2.1.73) and endo-beta(1,3)-glucanases (laminarinases, EC 3.2.1.39 and EC 3.2.1.6) have evolved to specifically hydrolyze these polysaccharides, respectively, in environmental niches including the human gut. To facilitate biochemical and structural analysis of these GHs, with a focus on MLGases, we present here the facile chemo-enzymatic synthesis of a library of active-site-directed enzyme inhibitors based on mixed-linkage oligosaccharide scaffolds and N-bromoacetylglycosylamine or 2-fluoro-2-deoxyglycoside warheads. The effectiveness and irreversibility of these inhibitors were tested with exemplar MLGases and an endo-beta(1,3)-glucanase. Notably, determination of inhibitor-bound crystal structures of a human-gut microbial MLGase from Glycoside Hydrolase Family 16 revealed the orthogonal labeling of the nucleophile and catalytic acid/base residues with homologous 2-fluoro-2-deoxyglycoside and N-bromoacetylglycosylamine inhibitors, respectively. We anticipate that the selectivity of these inhibitors will continue to enable the structural and mechanistic analyses of beta-glucanases from diverse sources and protein families.

Orthogonal Active-Site Labels for Mixed-Linkage endo-beta-Glucanases.,Jain N, Tamura K, Dejean G, Van Petegem F, Brumer H ACS Chem Biol. 2021 May 14. doi: 10.1021/acschembio.1c00063. PMID:33988963^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.