Glycoblotting enables seamless and straightforward workflow for MALDI‐TOF/MS‐based sulphoglycomics of N‐ and O‐glycans

Abstract

AbstractSulfated N‐ and O‐glycans exist in trace levels which are challenging to detect, especially when abundant neutral and sialylated glycans are present. Current matrix‐assisted laser desorption ionization‐time‐of‐flight mass spectrometry (MALDI‐TOF MS)‐based sulfoglycomics approaches effectively utilize permethylation to discriminate sulfated glycans from sialyl‐glycans. And a charge‐based separation to isolate the sulfated glycans from the rest of the permethylated neutral and sialyl‐glycans. However, these approaches suffer from concomitant sample losses during cleanup steps. Herein, we describe Glycoblotting as a straightforward complementary method with seamless glycan purification, enrichment, methylation, and labeling on a single platform to address sulfated glycan enrichment, sialic acid methylation, and sample loss. Glycoblottings’ on‐bead chemoselective ligation of reducing sugars with hydrazide showed excellent recovery of sulfated glycans, allowing the detection of more sulfated glycan species. On‐bead methyl esterification of sialic acid using 3‐methyl‐1‐p‐tolyltriazene (MTT) effectively discriminates sulfated glycans from sialyl‐glycans. Furthermore, we have shown that using MTT as a methylating agent allowed us to simultaneously detect and differentiate sulfate from phosphate groups in isobaric N‐glycan species. We believe that Glycoblotting will contribute significantly to the MALDI‐TOF MS‐based Sulphoglycomics workflow.