Sphingomyelins, sphingolipids and gangliosides

Ann and Adams (1993) have explored the use of alkali metal ions as adducts to improve structural determination of other types of sphingolipids. CID spectra of [M + Cat] ions (Caf = alkali metal ions) of ceramides and neutral glycosphingolipids provide immediate information about the lengths of the sphingolipid base and A -acyl chains and, most importantly, the locations of substituents on the A -acyl chain. 

Kwon et al. (1996) used ES/MS to characterize the content and composition of SPH isolated from pancreatic islets. More than four molecular species were identified with the most abundant of which containing sphingosine as the long-chain base and palmitic acid as the acyl chain, but stearoyl and arachidoyl species were also found. 

Taki et al. (1995) and Isobe et al. (1996) reported the application of TLC/ MS. Glycosphingolipids developed by TLC were transferred to a polyvinyl-idene difluoride membrane by TLC blotting, after which the glycosphingolipid band on the membrane was excised and placed on a direct probe tip and a few microlitres of triethanolamine was added as the matrix. The sample was analysed by secondary ion MS. The glycosphingolipids on the membrane were bombarded with a 20 kV caesium beam. 

The general methods of MS analysis of the glycosphingolipids have been summarized by Murphy (1993) and by Peter-Katalinic (1994) who have suggested critical experimental sequences with FAB and derivatization procedures for efficient structural characterization of an unknown glycosphingolipid. Early attempts to analyse complex glycosphingolipids involved 

Wegener, Kobbe and Stoffel (1996) described a useful and very efficient microbore HPLC method for the resolution of minute amounts of gangliosides (e.g. serum or tumour specimens). One of the greatest advantages of the HPLC procedure described here over that of HPTLC is that native non-derivatized gangliosides are separated and can be analysed further by reversed-phase HPLC, GLC and MS. 

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