N-Azidoacetylmannosamine-mediated chemical tagging of gangliosides

Abstract

Peracetylated N-α-azidoacetylmannosamine (Ac4ManNAz) is metabolized by cells to CMP-azidosialic acid. It has been demonstrated previously that in this way azidosialic acid-containing glycoproteins are formed that can be labeled on the cell surface by a modified Staudinger ligation. Here, we first demonstrate that the same procedure also results in the formation of azidosialic acid-containing gangliosides. Deoxymannojirimycin, an inhibitor of N-glycan processing in proteins, decreases the total cell surface labeling in Jurkat cells by ∼25%. Inhibition of ganglioside biosynthesis with N-[5-(adamantan-1-yl-methoxy)-pentyl]1-deoxynojirimycin reduces cell surface labeling by ∼75%. In conclusion, exposure of cells to Ac4ManNAz allows in vivo chemical tagging of gangliosides.

Keywords

• N-acetylmannosamine
• iminosugar
• azide
• Staudinger ligation
• sialic acid
• chemical ligation