Novel cleavage of reductively aminated glycan-tags by N-bromosuccinimide to regenerate free, reducing glycans.

Glycans that are fluorescently tagged by reductive amination have been useful for functional glycomic studies. However, the existing tags can introduce unwanted properties to the glycans and complicate structural and functional studies. Here, we describe a facile method using N-bromosuccinimide (NBS) to remove the tags and efficiently regenerate free reducing glycans. The regenerated free reducing glycans can be easily analyzed by routine mass spectrometry or retagged with different tags for further studies. This new method can be used to efficiently remove a variety of fluorescent tags installed by reductive amination, including 2-aminobenzoic acid and 2-aminopyridine. NBS treatment essentially transforms the commonly used 2-aminobenzoic linkage to a cleavable linkage. It can be used to cleave printed glycans from microarrays and cleave neoglycopeptides containing a 2-aminobenzoic linker.