Analysis of oversulfation in a chondroitin sulfate oligosaccharide fraction from bovine aorta by nanoelectrospray ioniza
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Daniela G. Seidler and Hans Kresse Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Münster, Germany
Jasna Peter-Katalinic´ Institute for Medical Physics and Biophysics, Biomedical Analysis Department, University of Münster, Münster, Germany
A combination of negative ion nano-electrospray ionization Fourier-transform ion cyclotron resonance and quadrupole time-of-flight mass spectrometry was applied to analysis of oversulfation in glycosaminoglycan oligosaccharides of the chondroitin sulfate type from bovine aorta. Taking advantage of the high-resolution and high mass accuracy provided by the FT-ICR instrument, a direct compositional assignment of all species present in the mixture can be obtained. An oligosaccharide fraction containing mainly hexasaccharides exhibited different levels of sulfation, indicated by the presence of species with regular sulfation pattern as well as oversulfated oligosaccharides with one additional sulfate group. Oversulfation can be directly identified from the high-resolution/high mass accuracy FT-ICR mass spectra according to their specific isotopic fine structure. Location of sulfate groups was analyzed by Q-TOF MS and low-energy CID MS/MS. Tetrasulfated hexasaccharides were analyzed by use of collision-induced dissociation at variable collision energy for an unambiguous assignment of the attachment site of the sulfate groups by minimizing unspecific neutral losses. Cleavage of glycosidic bonds gave rise to B- and C-type ions and their respective complementary Y- and Z-type fragment ions. (J Am Soc Mass Spectrom 2007, 18, 179 –187) © 2007 American Society for Mass Spectrometry
P
roteoglycans (PGs) are ubiquitously distributed in connective tissue and on the cell surface of mammalian tissues. They are actively participating in cell growth, differentiation and morphogenesis [1–3]. PGs consist of a core protein to which glycosaminoglycan (GAG) chains are attached through a specific oligosaccharide linkage region. The major biological importance of GAGs derives especially from their recognition function as GAGs have been shown to possess active domains, which interact with a number of Published online November 7, 2006 Address reprint requests to Dr. J. Peter-Katalinic´, Institute for Medical Physics and Biophysics, Biomedical Analysis Department, University of Münster, Robert Koch Strasse 31, D-48149, Münster, Germany. E-mail: [email protected] * Equal contribution from both authors.
growth factors, cell membrane receptors, or other important functional proteins [4 – 8]. The polysaccharide structure of GAGs consists of alternating blocks with characteristic epimerization and sulfation patterns. With respect to the structural type of the disaccharide repeating unit, GAG chains are categorized into chondroitin sulfate (CS), dermatan sulfate (DS), heparan sulfate (HS), heparin, hyaluronic acid (HA), and keratan sulfate (KS) DS, previously called chondroitin sulfate B, and CS are structurally similar. In CS, the hexuronic acid within the repeating disac
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