Imidazolium-labeled glycosides as probes to harness glycosyltransferase activity in human breast milk

Imidazolium-labeled (ITag-) glycosides are used to harness the glycosyltransferase activity directly from human breast milk. The covalently attached ionic labels provide a bifunctional chemical handle that is used to monitor reaction progress by MS, as well as aid in product purification from complex mixtures. The technology is exemplified in the synthesis of biologically relevant oligosaccharide analogs, LacNAc-ITag, ITag-Lewis(x) and ITag-Lewis(a), in a matter of days from human breast milk without having to isolate specific enzymes.