Mass spectrometry oligosaccharide derivatives

Methyl glycosides are of their greatest use when only a few methylated sugars are anticipated, as with polysaccharides of simple structure and, in particular, with oligosaccharides. They are useful where identification must be based on peak profile and retention times, but, when characterization is to be achieved by mass spectrometry, other derivatives, such as alditol acetates, are preferable (see Section XXI,2 p. 30). Glycosides have the advantage over alditols that they may be hydrolyzed to the free sugar for further characterization. 

L. M. Mallis, H. M. Wang, D. Loganathan, and R. J. Linhardt. Sequence Analysis of Highly Sulfated, Heparin-Derived Oligosaccharides Using Fast Atom Bombardment Mass Spectrometry. Anal. Chem., 61(1989) 1453-1458. 

Mass spectrometry has been used successfully to establish the structure of sialic acids, and the type of their bonds in the oligosaccharide chain. For this purpose, the fragmentation of various derivatives containing both the cyclic and the acyclic forms of sialic acid has been comprehensively studied. The methyl esters of sialic acid methyl ketosides, obtained as a... 

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

Several endeavors are being directed towards identifying biomarkers that can serve as a surrogate indicator of disease severity, in terms of either overall disease burden or involvement of a particular organ/system in patients with an LSD. In mucopolysaccharidosis type I, the analysis of the levels of oligosaccharides derived from GAGs in cultured fibroblasts (as measured by electrospray ionization tandem mass spectrometry) combined with the residual a-L-iduronidase activity have been shown to distinguish patients with and without CNS involvement (Fuller et al.,... 

The methods outlined in the last three paragraphs give finally a mixture of monosaccharides or derivatives of monosaccharides to be analysed. This analysis is carried out using the chromatographic techniques described in Chapters 1 and 3, with a possible adapted transformation to render the molecules volatile. The combination of gas chromatography and mass spectrometry techniques is particularly useful. The chemical operations have been miniaturized in order to treat very small quantities of the sample. This was necessary because it is rare to have really large oligosaccharides in notable quantities. They often come from... 

J.-B. Lee, T. Hayashi, K. Hayashi, and U. Sankawa, Structural analysis of calcium spirulan (Ca-SP)-derived oligosaccharides using electrospray ionization mass spectrometry, J. Nat. Prod., 63(2000)136-138. 

Shen X, Perreault H (1999) Electrospray Ionization Mass Spectrometry of 1-Phenyl-3-methyl-5-pyrazolone Derivatives of Neutral and N-Acetylated Oligosaccharides. J Mass Spectrom 34 502... 

A. Application of Mass Spectrometry for Characterizing Oligosaccharide Derivatives... 

A. APPLICATIONS OF MASS SPECTROMETRY FOR CHARACTERIZING OLIGOSACCHARIDE DERIVATIVES... 

Mass spectrometry provides a rapid, sensitive method for the structural analysis of oligosaccharides and, especially in combination with g.l.c., offers a valuable technique for the analysis of oligosaccharides from natural sources and from polysaccharide hydrolyzates. Methyl ethers " or trimethylsilyl ethers are suitable derivatives for the g.l.c. separation of oligosaccharides. 

Mass spectrometry of per(trimethylsilyl)ated derivatives has enabled partial characterization of oligosaccharides obtained from cell walls of Mycobacterium tuberculosis and seeds of Aesculus hippocastanum L.i28b q-jjg structures of the oligosaccharides were then fully elucidated by the use of other chemical and spectroscopic methods. The mass spectra have been determined for a number of neutral and mono- and di-sialo glycosphingolipids as their per(trimethylsilyl) derivatives. At present, m.s. gives only limited information about the sequential order and the nature of the sugar moieties in this type of compound. 

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. ... 

In a series of papers, Kovd k and Bauer described their studies of the fragmentation patterns of uronic acids and acidic oligosaccharides Kovdcik and Kovd6 examined methyl 0-methyl-D-xylofuranosides, compounds sufficiently volatile to be subjected to mass spectrometry without prior formation of volatile derivatives. 

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. 

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