Mapping glycoproteins by their sugars

Researchers have devised a way to identify glycoproteins having specific sugar residues on a proteome-wide scale. The technique developed by Benjamin F. Cravatt of Scripps Research Institute, Chi-Huey Wong of Scripps and Academia Sinica, in Taiwan, and coworkers could aid understanding of the function of specific sugars and glycoproteins in cells and lead to diagnostic procedures for distinguishing healthy and diseased tissues by their sugar content (J. Am. Chem. Soc. 2007, 129, 7266). The team engineered cells to express alkyne-containing fucose or sialic acid analogs, which became incorporated into glycoproteins during biosynthesis. The researchers labeled the alkyne-containing sugar analogs with biotin, captured the biotin-derivatized glycoproteins on immobilized streptavidin, and analyzed them by liquid chromatography-mass spectrometry. In prostate cancer cells, they identified unknown sialylation sites in glycoproteins and sialylated glycoproteins known to be associated with tumor progression and/or metastasis. They are currently analyzing the results to determine the role sialic acid might play in cancer.