Chemoenzymatic Synthesis of Sulfated <i>N</i>-Glycans Recognized by Siglecs and Other Glycan-Binding Proteins
Kun Huang, Eleanor E. Bashian, Guanghui Zong, Corwin M. Nycholat, Ryan McBride, Margaryta Gomozkova, Shengyang Wang, Chin Huang, Digantkumar Chapla, Edward N. Schmidt, Matthew S. Macauley, Kelley W. Moremen, James C. Paulson, Lai‐Xi Wang
Abstract
High Resolution Image Download MS PowerPoint Slide Sulfated N -glycans are present in many glycoproteins, which are implicated in playing important roles in biological recognition processes. Here, we report the systematic chemoenzymatic synthesis of a library of sulfated and sialylated biantennary N -glycans and assess their binding to Siglecs and glycan-specific antibodies that recognize them as glycan ligands. The combined use of three human sulfotransferases, GlcNAc-6- O -sulfotransferase (CHST2), Gal-3- O -sulfotransferase (Gal3ST1), and keratan sulfate Gal-6- O -sulfotransferase (CHST1), resulted in asymmetric and symmetric branch-selective sulfation of the GlcNAc and/or Gal moieties of N -glycans. The extension of the sugar chain using α-2,3- and α-2,6-sialyltransferases afforded the sulfated and sialylated N -glycans. These synthetic glycans with different patterns of sulfation and sialylation were evaluated for binding to selected Siglecs and sulfoglycan-specific antibodies using glycan microarrays. The results confirm previously documented glycan-recognizing properties and further reveal novel specificities for these glycan-binding proteins, demonstrating the utility of the library for assessing the specificity of glycan-binding proteins recognizing sulfated and sialylated glycans.