Profiling sulfation/epimerization pattern of full-length heparan sulfate by NMR following cell culture 13C-glucose metabolic labeling.
Résumé
Through its ability to interact with proteins, heparan sulfate (HS) fulfills a large variety of functions. Protein binding depends on the level of HS sulfation and epimerization which are cell specific and dynamically regulated. Characterization of this molecule, however, has been restricted to oligosaccharide fragments available in large amount for structural investigation or to sulfate distribution through compositional analysis. Here we developed a 1H-13C 2D NMR-based approach, directly performed on HS isolated from 13C-labeled cell. By integrating the peak volumes measured at different chemical shifts, this non-destructive analysis enables to determine both the sulfation and the iduronic/glucuronic profiles of the polysaccharide. Applied to wild-type and N-deacetylase/N-sulfotransferase-deficient fibroblasts as well as to epithelial cells differentiation, it also gives insights into the functional relationships existing between HS biosynthetic enzymes. This approach should be of large interest to better understand HS changes that occur through physiologic regulations or during pathological development.