N-Azidoacetylgalactosamine-tetraacylated

N-Azidoacetylgalactosamine-tetraacylated (Ac4GalNAz) provides the first part of a simple and robust two-step technique that helps identify and characterize cell surface sialic acid-containing glycoproteins. The azide-modified protein can be detected by reaction with alkynes. For example alkynes labeled with a fluorescent probe or a biotin can be used. The acetyl groups increase cell permeability and allow the unnatural sugars to easily pass through the cell membrane. Carboxyesterases remove the acetyl groups once the monosaccharide is in the cell.