Mass spectroscopy Carbohydrates

Although a number of assays and technologies are available to characterize and test protein molecules, such as peptide mapping, protein sequencing, carbohydrate analysis, electrophoresis, ELISA, and mass spectroscopy, they are not as definitive as the methods used for small molecule drugs. Hence, the test for similarity is not as well defined in the case of proteins. However, as... 

W. S. York, H. van Halbeek, A. G. Darvill, and P. Albersheim, Structural analysis of xyloglu-can oligosaccharides by H-n.m.r. spectroscopy and fast-atom-bombardment mass spectrometry, Carbohydr. Res., 200 (1990) 9-31. 

The majority of reports have used electrospray ionization mass spectroscopy (ESI-MS) as an analytical detection method because of its sensitivity and the soft namre of its ionization procedure, which generally only leads to the detection of the molecular ions of the positive library members. Many separation techniques have been coupled to ESI-MS, including affinity chromatography (49), size exclusion chromatography (50, 51), gel filtration (52), affinity capillary electrophoresis (53-58), capillary isoelectric focusing (59), immunoaffinity ultrafiltration (60), and immunoaffinity extraction (61). ESI-MS has also been used alone (62) to screen a small carbohydrate library. Other examples reported alternative analytical techniques such as MALDI MS, either alone (63, 64) or in conjunction with size exclusion methods (65), or HPLC coupled with immunoaffinity deletion (66). 

Sequencing of carbohydrates by using MALDI-TOF mass spectroscopy (p. 319)... 

Spectra, infrared, of carbohydrates, 12,13-33 Spectrometry, mass, of carbohydrate derivatives, 21,39-93 Spectroscopy, infrared, and carbohydrate chemistry, 19,23-49 Sphingosines, conjugates with sugars, 24, 381-433 Starch,... 

Historically, developments in chromatography led to a marked growth in research on polysaccharides and carbohydrate-containing biopolymers, which commonly entailed glycol-cleavage oxidation. With time, NMR spectroscopy and mass spectroscopy have acquired complementary roles of ever-increasing importance in studies on molecular structure. 

Oligosaccharides and Complex Carbohydrates. The lactonization of a-AT-acetylneuraminyl-(2- >3)-lactose has been studied by NMR and FAB mass spectroscopy. ... 

This reaction was first reported by MacDonald and Fischer in 1952. It is the degradation of hexoses into pentoses involving the steps of formation of dithioacetal, oxidation to unsaturated disulfone by means of perphthalic acid, hydrazine treatment, and benzalde-hyde splitting of the corresponding hydrazone. Therefore, the whole process is known as the MacDonald-Fischer degradation. In addition, when the unsaturated disulfone is dissolved in aqueous ammonia or methanol saturated with ammonia, 2-deoxy-2-amino sugar is resolved. This reaction in combination with mass spectroscopy was used to study the structure and stereochemistry of carbohydrates. ... 

Procedures for etherification and esterification of carbohydrates for GLC analysis, advantages and disadvantages of the different methods of hydroxyl and aldehyde group derivatization, columns used for the separation of the various derivatives, detection methods for GLC, mass spectroscopy and fast atom bombardment (FAB) as well as outlines of some strategies for structural analysis of carbohydrates are described, discussed and reviewed in an excellent book on the analyses of carbohydrates by GLC (35). 

The detection system employed, a pulsed amperometric detector, permits remarkable sensitivity (100 ppb), and provides the most sensitive workable commercially available detector yet developed for HPLC of under vatized carbohydrates. The drawback is that it requires strongly alkaline conditions for optimum carbohydrate oxidation (and detection). Eluants therefore contain high concentrations of non-volatile salts (typically sodium acetate and sodium hydroxide) and further structural elucidation or identification by e.g. mass spectroscopy and/or NMR requires prior desalting. The use of an anionic micromembrane suppressor downstream of the detector, thus converting the sodium hydroxide and sodium acetate to water and acetic acid, respectively, has been found satisfactory for NMR at 500 MHZ (86). However, with the inherent insensitivity of NMR and the low capacity of pellicular HPAEC columns, preparation for more sensitive analytical methods, e.g. MS, is desirable. Derivatization of fractionated oligosaccharides (either by methylation techniques or reductive coupling of 4-amino-ben oic acid ethyl ester, ABBE) and subsequent... 

Present day techniques for structure determination in carbohydrate chemistry are sub stantially the same as those for any other type of compound The full range of modern instrumental methods including mass spectrometry and infrared and nuclear magnetic resonance spectroscopy is brought to bear on the problem If the unknown substance is crystalline X ray diffraction can provide precise structural information that m the best cases IS equivalent to taking a three dimensional photograph of the molecule... 

N. A. Macleod, C. Johannessen, L. Hecht, L. D. Barron, and J. P. Simons, From the gas phase to aqueous solution Vibrational spectroscopy, Raman optical activity and conformational struc tore of carbohydrates. Int. J. Mass Spectrom. 253, 193 200 (2006). 

The separative power of l.c. can be coupled to various types of instruments in order to obtain additional qualitative information about eluted compounds. Two such instruments that may be coupled to l.c. include n.m.r. and mass spectrometers. Although there has been one report on the use of l.c.-n.m.r. spectroscopy in carbohydrate research, it is the... 

Mass spectrometry and high-resolution NMR spectroscopy, applicable to small samples of carbohydrate, yield essential information about sequence, configuration at anomeric and other carbons, and positions of glycosidic bonds. 

---