POLYSULFATED CARBOHYDRATES ANALYZED AS ION-PAIRED COMPLEXES WITH BASIC PEPTIDES AND PROTEINS USING ELECTROSPRAY NEGATIVE IONIZATION MASS-SPECTROMETRY

Electrospray ionization mass spectrometry was used in the negative ion mode to anlayze complexes of sucrose octasulfate, sucrose heptasulfat e and sulfated alpha-, beta- and gamma-cyclodextrins with syntheticall y prepared basic peptides, the basic protein ubiquitin and polyamines. The spectra presented demonstrate that complexes with these basic mol ecules facilitate the analysis of these polysulfated oligosaccharides. Stable (1:1) complexes result from the ion pairing between the proton ated basic arginine and lysine residues of the peptide and the anionic sulfate groups of the polysulfated oligosaccharides. Fragmentation of the polysulfated oligosaccharides resulting in the loss of SO3 could be suppressed by controlling the experimental conditions, such as the nozzle-skimmer voltage, used to obtain the spectre. In the absence of fragmentation, it was possible to obtain data on the purity of sucrose octasulfate and sucrose heptasulfate as well as the distribution of t he sulfated cyclodextrins. The confounding presence of sodium counter- ions is also eliminated using this method. Complete chemical sulfation of oligosaccharides is difficult to achieve. Thus, data on sample pur ity are essential for the characterization of sulfated oligosaccharide s used as pharmaceutical agents. (C) 1997 by John Whey & Sons, Ltd.