Highly sensitive sequencing of the sulfated domains of heparan sulfate

The heparan sulfates (HS) are hypervariable linear polysaccharides that act as membrane co-receptors for growth factors, chemokines, and extracellular matrix proteins. In most instances, the molecular basis of protein recogni tion by HS is poorly understood. We have sequenced 75% of the sulfated doma ins (S-domains) of fibroblast HS, including all of the major ones. This ana lysis revealed tight coupling of N- and 2-O-sulfation and a low frequency b ut precise positioning of 6-O-sulfates, which are required functional group s for MS-mediated activation of the fibroblast growth factors. S-domain seq uencing was conducted using a novel and highly sensitive method based on a new way of reading the sequence from high performance liquid chromatography separation profiles of metabolically labeled HS-saccharides following spec ific chemical and enzymatic scis-sion. The implications of the patterns see n in the sulfated domains for better understanding of the synthesis and fun ction of HS are discussed.