N-Azidoacetylmannosamine-mediated chemical tagging of gangliosides

Anton P. Bussink¹^,*, Paul F. van Swieten¹^,, Karen Ghauharali^*, Saskia Scheij^*, Marco van Eijk^*, Tom Wennekes, Gijs A. van der Marel, Rolf G. Boot^*, Johannes M. F. G. Aerts²^,* and Herman S. Overkleeft²^,

^* Department of Biochemistry, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands

Published, JLR Papers in Press, March 27, 2007.

^¹ A. P. Bussink and P. F. van Swieten contributed equally to thiswork.

^² To whom correspondence should be addressed. e-mail: j.m.aerts{at}amc.uva.nl (J.M.F.G.A.); h.s.overkleeft{at}chem.leidenuniv.nl (H.S.O.)

Peracetylated N- ${alpha}$ -azidoacetylmannosamine (Ac₄ManNAz) is metabolizedby cells to CMP-azidosialic acid. It has been demonstrated previouslythat in this way azidosialic acid-containing glycoproteins areformed that can be labeled on the cell surface by a modifiedStaudinger ligation. Here, we first demonstrate that the sameprocedure also results in the formation of azidosialic acid-containinggangliosides. Deoxymannojirimycin, an inhibitor of N-glycanprocessing in proteins, decreases the total cell surface labelingin Jurkat cells by $~$ 25%. Inhibition of ganglioside biosynthesiswith N-[5-(adamantan-1-yl-methoxy)-pentyl]1-deoxynojirimycinreduces cell surface labeling by $~$ 75%. In conclusion, exposureof cells to Ac₄ManNAz allows in vivo chemical tagging of gangliosides.

Supplementary key words N-acetylmannosamine • iminosugar • azide • Staudinger ligation • sialic acid • chemical ligation • cell surface labeling

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N-Azidoacetylmannosamine-mediated chemical tagging of gangliosides