Efficient Synthesis and Enzymatic Extension of an N-Glcnaz Asparagine Building Block

Session: 
S2.2 Protein N-glycosylation
Code: 
FL2.2.4
Location (hall): 
Mannose
Start/end time: 
Monday, July 1, 2019 - 15:30 to 15:35
Mikkel
Marqvorsen

Mikkel Marqvorsen1, Sivasinthujah Paramasivam2, Ward Doelman1, Antony Fairbanks2,3, Sander van Kasteren1

1Leiden Institute Of Chemsitry, Leiden University, Leiden, The Netherlands, 2Department Of Chemistry, University Of Canterbury, Christchurch, New Zealand, 3Biomolecular Interaction Centre, University Of Canterbury, Christchurch, New Zealand

N-Azidoacetyl-D-glucosamine (GlcNAz) is a particularly useful tool in chemical biology as the azide is a metabolically stable yet accessible handle within biological systems. In this work [1], we recently reported a practical synthesis of FmocAsn(N-Ac3GlcNAz)OH, a building block for solid phase peptide synthesis (SPPS). Protecting group manipulations were minimised by taking advantage of the inherent chemoselectivity of phosphine-mediated azide reduction, and the resulting glycosyl amine was employed directly in the opening of Fmoc protected aspartic anhydride. We demonstrated one potential application of the building block by establishing it as a substrate for enzymatic glycan extension using sugar oxazolines of varying size and biological significance with several endo-β-N-acetylglucosaminidases (ENGases). The added steric bulk resulting from incorporation of the azide was shown to have no or a minor impact on the yield of enzymatic glycan extension.

Assembly of complex, bioorthogonally labelled N-glycosylated asparagine for SPPS was achieved by selective Staudinger-type azide reduction, direct glycosyl amine coupling to aspartic anhydride, and finally enzymatic glycan extension.

References: 
  1. Marqvorsen, M. H. S.; Paramasivam, S.; Doelman, W.; Fairbanks, A. J.; van Kasteren, S. I. Efficient synthesis and enzymatic extension of an N -GlcNAz asparagine building block. Chem. Commun. 2019, 55, 5287–5290.

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