14419-60-4Relevant academic research and scientific papers
O-GlcNAcase catalyzes cleavage of thioglycosides without general acid catalysis
Macauley, Matthew S.,Stubbs, Keith A.,Vocadlo, David J.
, p. 17202 - 17203 (2007/10/03)
O-GlcNAcase catalyzes the removal of N-acetylglucosamine residues from serine and threonine residues of post-translationally modified proteins using a catalytic mechanism involving substrate-assisted catalysis and general acid/base catalysis. Since thioglycosides are widely perceived as resistant to hydrolysis by glycosidases, it was surprising to find that O-GlcNAcase also catalyzes the efficient hydrolysis of S-glycosides. Bronsted analyses and pH-activity studies of the O-GlcNAcase-catalyzed hydrolysis of a series of aryl S- and O-glycosides reveal that O-GlcNAcase effects hydrolysis of thioglycosides without the assistance of general acid catalysis. α-Deuterium kinetic isotope effects for O- and S-glycosides, as well as Taft-like analyses using N-fluoroacetyl-β-glycosides, suggest that O-GlcNAcase accomplishes hydrolysis of thioglycosides by stabilizing late transition states. For S-glycosides this transition state shows greater nucleophilic participation from the 2-acetamido group than for O-glycosides. The rate constants governing the O-GlcNAcase-catalyzed hydrolysis of O- and S-glycosides as compared to those previously determined for the spontaneous hydrolysis of structurally similar O,O- and O,S-acetals show a similar ratio. O-GlcNAcase therefore demonstrates similar catalytic proficiency toward both O- and S-glycosides. We conclude that O-GlcNAcase is a bifunctional catalyst capable of efficiently cleaving thioglycosides without general acid catalysis, an observation that may have biological implications. Copyright
Carbohydrate protein interactions. Syntheses of agglutination inhibitors of wheat germ agglutinin by phase transfer catalysis
Roy, Rene,Tropper, Francois D.
, p. 817 - 821 (2007/10/02)
Starting from chloride 1, a series of para-substituted aryl 2-acetamido-2-deoxy-β-D-glucopyranosides were prepared using phase transfer catalysis conditions with tetrabutylammonium hydrogen sulfate in 1 M sodium hydroxide and methylene chloride at room temperature.Zemplen de-O-acetylation afforded the unprotected glycosides.Optimization of reaction conditions was evaluated.Several functional group manipulations were effected to widen the number and nature of the para-substituents. Key words: phase transfer catalysis, aryl 2-acetamido-2-deoxy-β-D-glucopyranosides.
