Biologically relevant metal-cation binding induces conformational changes in heparin oligosaccharides as measured by ion mobility mass spectrometry

► Collision cross sections of heparin octasaccharides coordinated with and without metal ions were determined using ion mobility mass spectrometry. ► Metal ions induce a conformational change of heparin octasaccharide structure. ► Conformational changes observed in the gas phase with calcium ion coordinated heparin octasaccharide were consistent with that in solution.