Systematic chemoenzymatic synthesis of O-sulfated sialyl Lewis x antigens† †Electronic supplementary information (ESI) available: Materials, experimental details of the synthesis, analytical data of 4–10, 1a–3a, and 1b–3b, and NMR spectra of synthesized compounds. See DOI: 10.1039/c5sc04104j Click here for additional data file.

O-Sulfated sialyl Lewis x antigens play important roles in nature. However, due to their structural complexity, they are not readily accessible by either chemical or enzymatic synthetic processes. Taking advantage of a bacterial sialyltransferase mutant that can catalyze the transfer of different sialic acid forms from the corresponding sugar nucleotide donors to Lewis x antigens which are fucosylated glycans as well as an efficient one-pot multienzyme (OPME) sialylation system, O-sulfated sialyl Lewis x antigens containing different sialic acid forms and O-sulfation at different locations were systematically synthesized by chemoenzymatic methods.