MALDI mass spectrometry as a tool for characterizing glycosaminoglycan oligosaccharides and their interaction with proteins.

Matrix-Assisted Laser Desorption Ionization (MALDI) mass spectrometry (MS) has emerged as a powerful, sensitive technique for structural analysis of glycosaminoglycans (GAGs) and their fractions and fragments. Whereas the molecular size of low sulfated or nonsulfated species (such as low-molecular weight [LMW] K5 polysaccharides) can be directly determined up to molecular weights (MWs) of 12 kD, polysulfated species require complexing with a basic polypeptide and at present can be characterized (in terms of both MW and end residues) up to the size of a decasaccharide, even in complex mixtures. MALDI spectra of GAG oligosaccharides in the presence of a complexing protein permit to assess binding to the protein and the presence of multimeric complexes.