On-line NMR detection of microgram quantities of heparin-derived oligosaccharides and their structure elucidation by microcoil NMR |
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Authors: | Albert K Korir Cynthia K Larive |
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Institution: | (1) Department of Chemistry, University of California, Riverside, CA 92521, USA |
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Abstract: | The isolation and purification of sufficient quantities of heparin-derived oligosaccharides for characterization by NMR is
a tedious and time-consuming process. In addition, the structural complexity and microheterogeneity of heparin makes its characterization
a challenging task. The improved mass-sensitivity of microcoil NMR probe technology makes this technique well suited for characterization
of mass-limited heparin-derived oligosaccharides. Although microcoil probes have poorer concentration sensitivity than conventional
NMR probes, this limitation can be overcome by coupling capillary isotachophoresis (cITP) with on-line microcoil NMR detection
(cITP-NMR). Strategies to improve the sensitivity of on-line NMR detection through changes in probe design and in the cITP-NMR
experimental protocol are discussed. These improvements in sensitivity allow acquisition of cITP-NMR survey spectra facilitating
tentative identification of unknown oligosaccharides. Complete structure elucidation for microgram quantities of the purified
material can be carried out through acquisition of 2D NMR spectra using a CapNMR microcoil probe.
Survey NMR spectrum obtained by cITP-NMR using a second-generation probe (the microcoil of which is shown) facilitates tentative
identification of unknown oligosaccharides (e.g., the heparin-derived tetrasaccharide illustrated) |
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Keywords: | Heparin Microcoil NMR Capillary isotachophoresis Glycosaminoglycans Structure elucidation |
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