Isolation and Purification of Gangliosides from Plasma

The high degree of structural diversity of this class of lipids and alterations in the cellular ganglioside complement associated with differentiation and with the neoplastic state have suggested that particular gangliosides may be markers for certain tumors. The degree of purification necessary to resolve individual plasma gangliosides by thin-layer chromatography has, using available methodology, required larger volumes of plasma and sometimes is associated with significant losses during purification. The method described in this chapter was originally developed to address the specific problem of the purification of gangliosides from small volumes of biological fluids in which the ganglioside concentration is low. The procedure results in highly resolved ganglioside thin-layer chromatographic patterns using small (l.0-ml) samples of human plasma. The first step of the overall three-step-procedure is total lipid extraction of the plasma sample. Next, gangliosides are separated from most other lipids, and then the lower aqueous phase that results from this partition and which contains the gangliosides is purified by gel filtration to remove low molecular weight contaminants, both inorganic (salts) and organic (polypeptides). The gangliosides then can be quantitated and qualitatively analyzed by thin-layer chromatography. The chapter discusses the applications of the partition method for ganglioside isolation and purification.