Heterogeneity in Glycoproteins

Differences in the structure of glycoproteins can manifest themselves in a number of ways. Perhaps the first point to be emphasized is that the nature of the polypeptide chain to which oligosaccharide moieties become attached is not always the same. This is a situation that we have already discussed in connection with certain of the glycosaminoglycans (see p. 440). 

A number of other proteins are now known to exhibit heterogeneity with respect to their carbohydrate content these include pig pancreatic ribonuclease,9 rabbit19 and human109-238 -yG immunoglobulin, ceruloplasmin,239 2-acetamido-2-deoxy-/3-D-glucosidase,240 and the blood-group substances from ovarian cysts.145,241 

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Mortz, E., Sareneva, T., Julkunen, 1., and Roepstorff, P. (1996) Does matrix-assisted laser desorption/ionization mass spectrometry allow analysis of carbohydrate heterogeneity in glycoproteins A study of natural human interferon-gamma. J. Mass Spectrom., 31, 1109-1118. 

N. Kawasaki, M. Ohta, S. Hyuga, O. Hashimoto, and T. Hayakawa, Analysis of carbohydrate heterogeneity in a glycoprotein using liquid chromatography/mass spectrometry and liquid chromatography with tandem mass spectrometry, Anal. Biochem., 269 (1999) 297-303. 

The molecular mass of the intact glycoprotein is determined, in most cases using MALDl-MS, because this suffers less from the heterogeneity in the glycans. 

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