AN ELECTROSPRAY-IONIZATION TANDEM MASS-SPECTROMETRY METHOD FOR DETERMINATION OF THE ANOMERIC CONFIGURATION OF GLYCOSYL 1-PHOSPHATE DERIVATIVES

A rapid, simple, and sensitive method is described for the determinati on of the anomeric configuration of sugar 1-phosphates, sugar nucleoti des, and polyisoprenyl-phospho-sugars. Negative-ion electrospray ioniz ation of picomole amounts of glycosyl 1-phosphate derivatives produces an intense signal of the [M-H](-) deprotonated molecule which, by col lision-induced dissociation, decomposes in a characteristic manner dep ending on cis/trans configuration of the 2-hydroxyl and phosphate grou ps of the glycosyl residue. A distinct feature of the product ion spec tra of glycosyl 1-P and polyisoprenyl-P-sugars with cis configuration is the presence of abundant ions that correspond to the [M-H2O-H](-) d ehydration product and the [R-PO4(C2H3O])(-) fragment arising from a c leavage across the sugar ring, where R is -H or -polyprenyl/dolichyl f or glycosyl 1-P and polyisoprenyl-P-sugar, respectively. These two fra gments, [M-H2O-H](-) and [R-PO4-(C2H3O)](-), are absent from the produ ct ion spectra of sugar 1-P and polyisoprenyl-P-sugars with trans conf iguration. For sugar nucleotides, compounds with cis configuration pro duce, in tandem mass spectrometry, only one abundant fragment of nucle oside monophosphate, whereas those with trans configuration give nucle oside diphosphate as a major fragment ion. Accordingly, the anomeric c onfiguration of a glycosyl l-phosphate derivative can be easily determ ined by using electrospray-ionization tandem mass spectrometry provide d that the glycosyl residue of known absolute configuration has a free 2-hydroxyl group and no other charge location. (C) 1998 Academic Pres s.