- Synthesis and Characterization of Versatile O-Glycan Precursors for Cellular O-Glycomics
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Protein O-glycosylation is a universal post-translational modification and plays essential roles in many biological processes. Recently we reported a technology termed cellular O-glycome reporter/amplification (CORA) to amplify and profile mucin-type O-glycans of living cells growing in the presence of peracetylated Benzyl-α-GalNAc (Ac3GalNAc-α-Bn). However, the application and development of the CORA method are limited by the properties of the precursor benzyl aglycone, which is relatively inert to further chemical modifications. Here we described a rapid parallel microwave-assisted synthesis of Ac3GalNAc-α-Bn derivatives to identify versatile precursors for cellular O-glycomics. In total, 26 derivatives, including fluorescent and bioorthogonal reactive ones, were successfully synthesized. The precursors were evaluated for their activity as acceptors for T-synthase and for their ability to function as CORA precursors. Several of the precursors possessing useful functional groups were more efficient than Ac3GalNAc-α-Bn as T-synthase acceptors and cellular O-glycome reporters. These precursors will advance the CORA technology for studies of functional O-glycomics.
- Zhang, Qing,Li, Zhonghua,Chernova, Tatiana,Saikam, Varma,Cummings, Richard,Song, Xuezheng,Ju, Tongzhong,Smith, David F.,Wang, Peng G.
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- Synthesis of 4-methylumbelliferyl glycosides for the detection of α- and β-D-galactopyranosaminidases
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Reaction at room temperature of either 3,4,6-tri-O-acetyl-2-azido-2-deoxy-α- of β-D-galactopyranosyl chloride with a twofold excess of 4-methylumbelliferone and silver trifluoromethanesulfonate in dichloromethane containing an equimolar amount of sym-collidine yielded 4-methylumbelliferyl tri-O-acetyl-2-azido-2-deoxy-α-D-galactopyranoside in 33percent yield.The β anomer was formed in 20 and 10percent yields, respectively.Reduction of the azido group, acetylation followed by de-O-acetylation, provided the desired 4-methylumbelliferyl 2-acetamido-2-deoxy-α- and β-D-galactopyranosides (N-acetyl-α- and β-D-galactopyranosaminides).The α-glycoside proved to be an effective substrate for the highly sensitive fluorimetric detection of N-acetyl-α-D-galactopyranosaminidase activity in human tissues and was used to examine the deficiency of this activity, which is the enzymatic defect in Schindler disease.Key words: synthesis of 4-methylumbelliferyl N-acetyl-α- and β-D-galactopyranosaminides, N-acetyl-α-D-galactosaminidase deficiency (Schindler disease).
- Szweda, R.,Spohr, U.,Lemieux, R. U.,Schindler, D.,Bishop, D. F.,Desnick, R. J.
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p. 1388 - 1391
(2007/10/02)
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