Streamlined Way To Label Glycoproteins

A novel method for labeling sialylated glycoproteins on animal cell surfaces could have important advantages for glycoproteomics—population studies of glycosylated proteins for cancer diagnostics and other applications (Nat. Methods, DOI: 10.1038/nmeth.1305). In current labeling techniques, reactive groups such as alkynes are introduced into cells as reagent-derivatized substrates that are taken up and incorporated into cell glycoproteins during biosynthesis. The new approach, developed by Philip E. Dawson, James C. Paulson, and coworkers at Scripps Research Institute, is the first to efficiently label cellular glycoproteins by direct synthesis. The researchers use periodate oxidation of diols in conjunction with aniline-catalyzed oxime ligation to add biotin tags to sialic acids on cell glycoproteins. The method is inexpensive and nontoxic, doesn't require growing cells in the presence of reagent- derivatized sugar precursors, and achieves 10- to 100-fold higher levels of labeling than with biosynthetic techniques.