Permethylated oligosaccharide, mass spectrometry

A. Dell, Preparation and desorption mass spectrometry of permethyl and peracetyl derivatives of oligosaccharide, Meth. Enzymol., 193 (1990) 647-660. 

Viseux, N., de Hoffmann, E. and Domon, B. (1997) Structural assignment of permethylated oligosaccharide subunits using sequential tandem mass spectrometry. Anal. Chem., 69, 3193-8. 

Solouki, T., Reinhold, B.B., Costello, C.E. et al. (1998) Electrospray ionization and matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry of permethylated oligosaccharides. Anal. Chem., 70 (5), 857-64. 

Much of our knowledge on the fragmentation patterns of carbohydrate derivatives arises from studies on methylated monosaccharides, but in structural investigations, such compounds are seldom subjected to mass spectrometry. On the other hand, the molecular weight of a permethylated oligosaccharide is significantly less than that of the per(trimethylsilyl) derivative. For this reason, the mass spectra of disaccharides as -their permethylated alditols have been determined by Chizhov and coworkers, Karkkainen, and Krone and Beckey. Trisaccharides have also been studied by Karkkainen, either as permethylated glycosides or as alditols. ... 

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., Costello, C. E. andDomon, B. Post-source decay mass spectrometry optimized calibration procedure and structural characterization of permethylated oligosaccharides. JMass Spectrom, 34,364,... 

N. Viseux, E. de Hoffmann, and B. Domon, Structural analysis of permethylated oligosaccharides by electrospray tandem mass spectrometry. Anal Chem. 69, 3193-3198 (1997). 

As early as the mid-1980s, the permethylation of oligosaccharides was applied to for their analysis when employing secondary ion mass spectrometry (SIMS) and fast atom bombardment (FAB). Indeed, with the advent of ESI and MALDI a few years later, this method of sample modification was foimd to be perfectly suitable for these techniques, given the enhancement in ionization efficiency that resulted from permethylation of the sample [63]. 

Mass Spectrometry (MS). MS is one of the key techniques used in structure determination of carbohydrates and analyses via electron impact (E.I.) and chemical ionization (C.I.) methods are performed routinely on low molecular weight permethylated or peracetylated carbohydrates. Recently, MS procedures have found wider application in the structure elucidation of less volatile higher molecular weight oligosaccharides as a result of instrumental developments (in particular, desorption methods of ionization, based on fast atom bombardment (FAB) (93), field desorption (FD), laser desorption (LD), plasma desorption (PD), and secondary ion (SI) mass spectrometry) and improvements in derivatization techniques. For example, a series of malto-oligosaccharides, starch and other glycans have been examined with LD FD-MS (94,95) whilst FAB techniques have been employed for studies of cello- and malto-oligosaccharides (96) and branched cyclo-dextrins (97). 

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