Volume 388, Number 8, 1707-1716, DOI: 10.1007/s00216-007-1400-2

On-line NMR detection of microgram quantities of heparin-derived oligosaccharides and their structure elucidation by microcoil NMR

Albert K. Korir and Cynthia K. Larive

From the issue entitled "New Plasma Discharges for Atomic Spectrometry"

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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.
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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)

Keywords  Heparin - Microcoil - NMR - Capillary isotachophoresis - Glycosaminoglycans - Structure elucidation

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