Chemoenzymatic synthesis of the oligosaccharide moiety of the tumor-associated antigen disialosyl globopentaosylceramide

Disialosyl globopentaosylceramide (DSGb5) is often expressed by renal cell carcinomas. To investigate properties of DSGb5, we have prepared its oligosaccharide moiety by chemically synthesizing Gb5 which was enzymatically sialylated using the mammalian sialyltransferases ST3Gal1 and ST6GalNAc5. Glycan microarray binding studies indicate that Siglec-7 does not recognize DSGb5, and preferentially binds Neu5Acα(2,8)Neu5Ac containing glycans. The oligosaccharide of the tumor-associated antigen DSGb5 was synthesized in a chemoenzymatic manner by exploiting the mammalian glycosyl transferases ST3Gal1 and ST6GalNAc5, and its binding with Siglec-7 was investigated by glycan microarray technology.