Preparation of Oligosaccharides from Sulfated Glycosaminoglycans Using Bacterial Enzymes

Although the polysaccharide backbone Glycosaminoglycans (GAGs) have been demonstrated to interact with a variety of proteinsand such interactions are thought to be involved in the regulation of the physiological functions of these proteins (
1
). Although the polysaccharide backbone of GAGs is a linear polymer composed of alternating amino sugar and hexuronic acidresidues, this simple repeat structure acquires a considerable degree of variability by extensive modifications involvingsulfations and uronate epimerization (
2
). The structural variability is the basis for the wide variety of domain structures with biological activities (
1
). Investigation of the structure-function relationship of GAGs has been hindered by the difficulty in microanalyzing theircomplicated structure. GAG molecules are so heterogeneous that sequence analysis on unfractionated GAG chains can give onlystatistical structural information. Actual sequencing is possible, however, on oligosaccharide fragments, which can be obtainedby chemical or enzymatic degradation of GAG chains followed by separation by means of various chromatographies. In this chapter,we describe the methods for enzymatic degradation of GAG chains and fractionation of the oligosaccharide products. Becausemany kinds of highly purified GAG-degrading enzymes, which are not contaminated by sulfatases, are commercially availableand cleave polysaccharides with high specificities under mild conditions, enzymatic cleavage is a useful method for the preparationof GAG oligosaccharides.