Oligosaccharides permethylated, structure analysis

N. Viseux, E. de Hoffmann, B. Domon, Structural analysis of permethylated oligosaccharides byESI-MS-MS, Anal. Chem., 69 (1997) 3193. 

The use of mass spectrometry in the structural analysis of carbohydrates, first reported in 1958 (114), was developed in detail by Kochetkov and Chizhov (115). They showed that, under electron impact, the acetylated and methyl ether derivatives of monosaccharides provided a wealth of structural information through analysis of typical fragmentation pathways of the initial molecular ion. This has proved of enormous utility in the structural elucidation of polysaccharides and complex oligosaccharides sequential permethylation, hydrolysis, reduction to the alditol, and acetylation, affords mixtures of peracetylated, partially methylated alditol acetates that can be separated and analyzed by use of a gas chromatograph coupled directly to a mass spectrometer (25). The mass spectra of stereoisomers are normally identical, while the gas chromatographic retention times readily permit differentiation of stereoisomers. 

ViSEUX, N. deHofemann, E. Domon, B. Structural analysis of permethylated oligosaccharides by electiospray tandem mass spectrometry. Anal. Chem. IW1,69, 3193-3198. 

A detailed study of the 0-linked oligosaccharides present on the surface of normal granulocytes, chronic myelogenous leukemia cells, and acute myelogenous leukemia cells has been completed. Structures were elucidated by f.a.b.-m.s. after permethylation, and methylation analysis before and after specific exo-glycosidase treatments. Some of the components were shown by f.a.b.-m.s. to be poly(N-acetyllactosaminyl) oligosaccharides, for example, 29. 

This method alone does not allow the determination of the structure of oligosaccharides. If, however, it is used in conjunction with an MS/MS analysis of the whole permethylated oligosaccharides, the complete structure can be deduced. 

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