Molecular species analysis of monosialogangliosides from sea urchin Strongylocentrotus nudus by RPLC-ESI-MS/MS.

Sea urchin gangliosides have been proved to contain neuritogenic activities, which related to their molecular compositions. This study reports a method utilizing reversed-phase chromatography coupled to mass spectrometry for structure investigation and molecular species determination of the monosialogangliosides from sea urchin Strongylocentrotus nudus. Two types of sulfated and nonsulfated monosialogangliosides were isolated from the sea urchin ovary. In MS(2) spectra of both nonsulfated monosialoganglioside and sulfated monosialoganglioside, 2-6 linked sialic acids were identified by the characteristic fragments of (0,4)A2-CO2 and (0,2)A1. Fragment ions at m/z 139.1 and m/z 169.1 of nonsulfated monosialoganglioside might be characteristic for 8-sulfated sialic acid residue. Retention time of the molecules was effectively used in the characterization of unknown molecules, and molecules that differ in mass by only 0.04 Da were easily differentiated.