[摘要]：solid-phase synthesis as models of internal glucosamines within heparan sulfate. An orthogonally protected 2'-hydroxyethyl GlcN deriv. was immobilized on a trityl resin support and subjected to regioselective deprotection and sulfonation conditions, which were optimized with the aid of on-resin IR or Raman anal. The sulfoforms were cleaved from the resin under mild Lewis acid conditions without affecting the O- or N-sulfate groups and purified by reversed-phase high-performance liq. chromatog. (HPLC). The a-GlcN sulfoforms and their 4-O-benzyl ethers were examd. by electrospray ionization tandem mass spectrometry (ESI-MS/MS), with product ion spectra produced by collision-induced dissocn. (CID). ESI-MS/MS revealed significant differences in parent ion stabilities and fragmentation rates as a function of sulfate position. Ion fragmentation by CID resulted in characteristic mass losses with strong correlation to the positions of both free hydroxyl groups and sulfate ions. Most of these fragmentation patterns are consonant with elimination pathways, and suggest possible strategies for elucidating the structures of glucosamine-derived sulfoforms with identical m/z ratios. In particular, fragmentation anal. can easily distinguish GlcN sulfoforms bearing the relatively rare 3-O-sulfate from isomers with the more common 6-O-sulfate.
