Streamlined gram-scale natural N-glycan production using reversible tagging after oxidative release of natural glycans

The study of natural glycans is fundamental to modern glycomics; however, the functional analysis of these glycans is limited by their low natural abundance, structural heterogeneity, and the absence of efficient preparative-scale isolation methods. Here, we present a streamlined approach for the gram-scale production of complex natural N-glycans in their reducing form by combining oxidative release of natural glycans (ORNG) using household bleach, an innovative cleavable tag chemistry, and optimized multi-dimensional chromatography. Our ORNG process releases N-glycans from kilogram-scale of natural sources containing various glycoproteins, which can be efficiently attached with a 4-aminobenzoate tag, facilitating the selective separation of these glycans from other biomolecules. The tagged glycans can be purified via dry-load HILIC flash chromatography at gram scale followed by reverse-phase HPLC. Treatment with Oxone quantitatively cleaves the tag, regenerating the free reducing N-glycans in high yield. This method provides an accessible, gram-scale source of complex N-glycans, including complex asymmetric structures that are challenging to synthesize through conventional chemoenzymatic approaches. We believe this approach represents a versatile strategy for acquiring complex natural glycans, opening new avenues for the functional exploration of N-glycans in glycoscience.