Reducing-end tagging

M. Li and J. A. Kinzer, Structural analysis of oligosaccharides by a combination of electrospray mass spectrometry and bromine isotope tagging of reducing-end sugars with 2-amino-5-bromopyridine, Rapid Commun. Mass Spectrom., 17 (2003) 1462-1466. 

Unless mass spectrometric analysis of the glycan pool is carried out, the released sugars need to be tagged to enable them to be detected during separation. Classically, the reducing end of the oligosaccharides had been reduced with alkaline sodium borotritide [132]. 

Chemical derivatization methods as an aid to MS analysis continue to be important. Derivatization can be divided into tagging of reducing ends and protection of most or all of the functional groups. Permethylation is still an important type of full derivatization. 

Hase, S., et al. (1978). Structure Analysis of Oligosaccharides by Tagging of the Reducing End Sugars with a Fluorescent Compound, BBRC 85 257-263. 

The sequence of an underivatized hetero-CHO can be deduced from the occurrence of °4A and 4A cross-ring fragments in MS of the pseudomolecular ion as well as MS of sodiated C-type ions (unpublished results from this laboratory). In this case, the sodium ion may be understood as a tag, which allows identification of the reducing end sugar. 

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