Advances in glycosaminoglycanomics by 15N-NMR spectroscopy

Recent developments to enhance sensitivity in solution NMR spectroscopy such as the advent and spread of the use of high magnetic fields, cryoprobe technology, isotopic labeling techniques, and new combinations of 2D experiments have pushed the limits in structural NMR analysis of glycosaminoglycans (GAGs). This review is dedicated to the less sensitive (15)N isotope of hexosamines rather than the commonly used anomeric and ring (1)H and (13)C resonances of uronic acids and hexosamines. Given that GAG types are basically classified on the basis of their composing hexosamine types together with variations of their sulfation patterns, and epimerized forms of the adjacent uronic acids, (15)N-related NMR studies on native GAGs, oligosaccharides, or the various composing amino sugars have proved to be quite useful in the retrieval of both structural and dynamic information, despite the low number of resultant peaks. This in turn reduces significantly chemical shift degeneracy and at the same time facilitates spin and structural assignments. This review covers the principal contributions made so far by solution (15)N-NMR spectroscopy to progress in the structural biology of GAGs in the current glycomics age.