Disaccharides mass spectrometry

Defaye, K. and Garcia Fernandez, J.M., Protonic and thermal activation of sucrose an the oligosaccaride composition of caramel. Carbohydrate Res., 256, Cl, 1994. Ratsimba, V. et al.. Qualitative and qnantitative evaluation of mono- and disaccharides in D-fructose, D-glucose and sucrose caramels by gas-liquid chromatography-mass spectrometry di-D-fructose dianhydrides as tracers of caramel authenticity, J. Chro-matogr. A, 844, 283, 1999. 

Peltier, J.M. MacLean, D.B. Szarek, W.A. Determination of the Glycosidic Linkage in Peracetylated Disaccharides Comprised of D-Glucopyranose Units by Use of Desorption Electron-Ionization Mass Spectrometry. Rapid Commun. Mass Spectrom. 1991,5,446-449. 

D-galactose, methyl a- and 0-D-glucopyranosides, and a number of disaccharides, thus demonstrating that mass spectrometry is useful in the field of carbohydrate chemistry. In this study, the appearance potentials of CjHnOs ions were measured, and the results interpreted in terms of greater stability of the /9-(d or l) (equatorial) anomer with respect to the o-(d or l) (axial) one in the CA conformation. 

The carbohydrate sequence of the major tetrasaccharlde was determined by examining the nitrous acid deamination products (25) as permethylated disaccharides by chemical ionization mode of gas chromatography/mass spectrometry. The products were identified as hexosyl-2,5-anhydromannitol and hexosyl-myoinositol,indicating that the major tetrasaccharide had the sequence Galp(l->4)GlcNAcp(l->4)Glcp(l- -2)Inos (Figure 5). 

B. Mulroney, J. C. Traeger, and B. A. Stone, Determination of both linkage position and anomeric configuration in underivatized glucopyranosyl disaccharides by electrospray mass spectrometry, J. Mass Spectrom., 30 (1995) 1277-1283. 

Figure 4 Coenzymes of methanogenesis. F-430, coenzyme M (2-thioethanesulfonate), and coenzyme B (7-thioheptanoyl-threonine-O-phosphate [sometimes abbreviated HS-HTP]). Methyl-reducing factor is a structure proposed on the basis of NMR and mass spectrometry, in which the phosphate group of CoB is linked by a carboxylic-phosphoric anhydride to a UDP disaccharide, uridine 5 -(2-acetamido-2-deoxymannopyranuronosyl)-2-acetamido-2-deoxy-glucopyranosyl-diphosphate [171]. The CoB moiety without it appears to be functionally active in the enzyme reaction.

Chapters 3 and 4 (familiarity with which is assumed) provide us with powerful techniques and methods to elucidate the structures of organic compounds especially when combined with information derived from IR and mass spectrometry. These NMR methods are collectively referred to as one-dimensional techniques. To extend our capabilities, we turn once more to NMR. We will use four compounds as examples ipsenol (see Chapter 3), caryophyllene oxide (a sesquiterpene epoxide), lactose (a j3-linked disaccharide), and a small peptide (valine-glycine-serine-glutamate, VGSE). The structures of these compounds are shown in Figure 5.1. 

The use of NCW as the mobile phase in liquid chromatography was recently reviewed. In this area, in addition to its green credentials, NCW is compatible with a range of detection methods flame ionization detection, mass spectrometry (MS) and UV (to short wavelengths). The reason for the recent growth in this area is the development of more thermally stable stationary phases. It has been used to analyse a growing number of analytes (alkylbenzenes, phenols, ketones, carboxylic acids, amino acids, carbohydrates and some pharmaceuticals). For example, carbohydrates (monosaccharides, disaccharides and sugar... 

Heparan sulfate-like oligomers 81 were assembled on a soluble PEG resin using repeating disaccharide building blocks (Fig. 14) [97]. The coupling efficiency was about 95% and, after deprotection and cleavage from the resin, the products were sulfated. The structure of the products was confirmed by H NMR and MALDI-mass spectrometry. 

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. ... 

Li, D. T., Sheen, J. F. and Her, G R. Structural analysis of chromophore-labeled disaccharides by capillary electrophoresis tandem mass spectrometry using ion trap mass spectrometry. J Am Soc Mass Spectrom, 11, 292, 2000. 

Ruiz-Calero, V., Moyano, E., Puignou, L. and Galceran, M. T. Pressure-assisted capillary electrophoresis-eleclrospray ion trap mass spectrometry for the analysis of heparin depolymerised disaccharides. J Chromatogr A, 914, 277, 2001. 

D. T. Li and G. R. Her, Strncmral analysis of chromophore-labeled disaccharides and oligosaccharides by electrospray ionization mass spectrometry and high-performance liquid chromatography/electrospray ionization mass spectrometry, J. Mass Spectrom. 33, 644-652 (1998). 

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