Matches in UGent Biblio for { ?s ?p Endo-β-N-acetylglucosaminidases (EC 3.2.1.96) are deglycosylating enzymes hydrolyzing the chitobiose core of N-linked glycans on glycoproteins and glycopeptides. These glycosidases are important tools for structural characterization of asparagine-linked oligosaccharides and are also applied for the chemo-enzymatical synthesis of glycosides and glycoproteins using their transglycosylating activities. The endo-β-N-acetylglucosaminidases classified into glycosyl hydrolase family 18 were originally thought to be found only in prokaryotes. A new subgroup has only recently been discovered: Endo-T from the ascomycete Trichoderma reesei [1] and Endo-FV from the basidiomycete Flammulina velutipes [2] are the first characterized representatives. The Endo-T activity is responsible for the extensive N-deglycosylation observed for several T. reesei (hemi)-cellulases but its biological function is still unknown. The enzyme has been overexpressed, purified and biochemically characterized. The activity on N-glycans (Man5GlcNAc2) and on a glycoprotein (RNase B) was determined and compared with the bacterial enzyme Endo-H from Streptomyces plicatus. It could be demonstrated that proteolysis at the C-terminus with a 43-49 amino acid peptide is essential for the enzymes activity. This post-secretorial processing could be part of a protection and activation mechanism to avoid deglycosylation of important intracellular proteins. The three-dimensional structure of Endo T was solved to 1.3 Å resolution [3] and co-crystallisation of the enzyme with Man5GlcNAc was also successful. The protein has a complete (β/α)8 Tim-barrel topology although a large C-terminal peptide is missing. Since the peptide following the α8-helix in Endo-T is absent in the structure, we can only speculate on its position and interference with substrate binding. This large peptide could potentially fold into a second domain or fold back and approach the binding cleft. Comparison with the structure of Endo F3 from Elizabethkingia meningosepticum in complex with an octasaccharide biantennary oligosaccharide [4] shows a different binding mode. Further research aims at structure determination of the intact protein. (1) Stals, I., B. Samyn, et al. (2010) FEMS Microbiol Lett, 303, 9-17; (2) Hamaguchi, T., T. Ito, et al. (2010) Glycobiology, 20, 420-432; (3) Karkehabadia, S., Stals, I., et al. (2011) manuscript submitted; (4) Waddling C.A., Plummer T.H. et al. (2000) Biochemistry, 39, 7878-7885. }
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- aggregation abstract "Endo-β-N-acetylglucosaminidases (EC 3.2.1.96) are deglycosylating enzymes hydrolyzing the chitobiose core of N-linked glycans on glycoproteins and glycopeptides. These glycosidases are important tools for structural characterization of asparagine-linked oligosaccharides and are also applied for the chemo-enzymatical synthesis of glycosides and glycoproteins using their transglycosylating activities. The endo-β-N-acetylglucosaminidases classified into glycosyl hydrolase family 18 were originally thought to be found only in prokaryotes. A new subgroup has only recently been discovered: Endo-T from the ascomycete Trichoderma reesei [1] and Endo-FV from the basidiomycete Flammulina velutipes [2] are the first characterized representatives. The Endo-T activity is responsible for the extensive N-deglycosylation observed for several T. reesei (hemi)-cellulases but its biological function is still unknown. The enzyme has been overexpressed, purified and biochemically characterized. The activity on N-glycans (Man5GlcNAc2) and on a glycoprotein (RNase B) was determined and compared with the bacterial enzyme Endo-H from Streptomyces plicatus. It could be demonstrated that proteolysis at the C-terminus with a 43-49 amino acid peptide is essential for the enzymes activity. This post-secretorial processing could be part of a protection and activation mechanism to avoid deglycosylation of important intracellular proteins. The three-dimensional structure of Endo T was solved to 1.3 Å resolution [3] and co-crystallisation of the enzyme with Man5GlcNAc was also successful. The protein has a complete (β/α)8 Tim-barrel topology although a large C-terminal peptide is missing. Since the peptide following the α8-helix in Endo-T is absent in the structure, we can only speculate on its position and interference with substrate binding. This large peptide could potentially fold into a second domain or fold back and approach the binding cleft. Comparison with the structure of Endo F3 from Elizabethkingia meningosepticum in complex with an octasaccharide biantennary oligosaccharide [4] shows a different binding mode. Further research aims at structure determination of the intact protein. (1) Stals, I., B. Samyn, et al. (2010) FEMS Microbiol Lett, 303, 9-17; (2) Hamaguchi, T., T. Ito, et al. (2010) Glycobiology, 20, 420-432; (3) Karkehabadia, S., Stals, I., et al. (2011) manuscript submitted; (4) Waddling C.A., Plummer T.H. et al. (2000) Biochemistry, 39, 7878-7885".