Glycoproteins spectroscopy

Amide derivatives have proved especially useful sugars for study by c.d. spectroscopy. The amide substituent is the same as the chromophore found in proteins, so that its optical properties have been extensively studied both experimentally and theoretically. 2-Acetamido sugars are found in many glycoproteins. The structure of 2-acetamido-2-deoxy-a-D-glucopyranose is given as an example in formula 7. 

The complex oligosaccharides comprising the Y and T antennae of three glycoproteins have been studied by c.d. spectroscopy. Five antennae were studied in all, because two of the proteins have two closely related forms. The c.d. for the three fundamental oligosaccharides are given in Fig. 36. These are asparagine-linked glycopeptides, and the intense, conservative c.d. band that results from the interaction between the two amides has already been discussed in Section III,2. Fig. 36 shows that the c.d. spectra... 

Specific applications of carbon-13 n.m.r. spectroscopy to the glycophorins, an important family of glycoproteins present in the human erythrocyte membrane, are discussed by K. Dill (Clemson), who demonstrates the value of C-n.m.r. spectra for the structural mapping of glycoproteins. 

Natural-abundance, 13C-n.m.r. spectroscopy is not a technique that may be applicable to all systems. It does have a few drawbacks, despite its overall, positive appeal. The relatively low gyromagnetic ratio of carbon-13, its low sensitivity, and its low natural abundance do present some handicaps.33 However, these factors are outweighed by the large chemical-shift range for carbon atoms in glycoproteins (—200 p.p.m.) and the fact that glycoproteins contain a multitude of carbon atoms... 

Recent Developments in the Use of 13C-N.m.r. Spectroscopy for the Structural Analysis of Oligosaccharides of Glycoproteins... 

VI. Summary of the Application of 13C-N.m.r. Spectroscopy to the Study of Glycoproteins, and Possible Future Uses... 

Vliegenthart, J.F.G., Dorland, L., and van Halbeek, H. (1983) High-resolution, lH-nuclear magnetic resonance spectroscopy as a tool in the structural analysis of carbohydrates related to glycoproteins. Adv. Carbohydr. Chem. Biochem. 41, 209-374. 

Dell, A. Morris, H.R. (2001) Glycoprotein structure determination by mass spectroscopy. Science 291, 2351-2356. 

In the polysaccharide and the glycoprotein series, permethylated derivatives are almost exclusively used for their solvolytic decomposition and for the analysis of the mono- and oligo-saccharides formed, whereas, in the glycosphingolipid series, the investigation of the permethylated derivatives themselves by physicochemical methods has acquired great importance. They proved to be very convenient both for mass-spectrometric analysis and for n.m.r. spectroscopy (see later). 

Ten sialic-acid-containing oligosaccharides and four neutral oligosaccharides have been purified from the major glycoprotein fraction of hog, submaxillary-gland mucin. H-N.m.r. spectroscopy at 360 MHz, in combination with methylation analysis and mass spectrometry, allowed the determination of their structures, which are partial structures of a pentasaccharide (see Fig. 42) having blood-group A activity.221... 

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