Resolution of structural isomers of sialylated oligosaccharides by capillary electrophoresis

The resolution of structural isomers in mixtures of oligosaccharides is oft en challenging. Capillary electrophoresis was employed to separate three se ts of structural isomers of sialylated oligosaccharides found in human milk and bovine colostrum. Different running buffers were necessary to achieve optimal baseline resolution. To resolve 3'- and 6'-sialyllactoses, 0.2 M aq ueous sodium phosphate containing 40% methanol as an organic modifier was u sed as a running buffer. To resolve 3'- and 6'-sialyllactosamines, 0.4 M aq ueous sodium phosphate without organic modifier was used. Baseline resoluti on of sialyllacto-N-tetraose-a and -b and sialyllacto-N-neotetraose-c was a chieved with a 0.4 M Tris-HCl buffer containing 250 mM sodium dodecyl sulfa te and 10% methanol as the organic modifier. Thus, each of these sets of st ructural isomers of sialylated oligosaccharides required a unique running b uffer with respect to buffer type, concentration, pH, presence of organic m odifiers, and surfactants. Similar electrophoresis conditions may be useful for resolving and analyzing other structural isomers of acidic oligosaccha rides by capillary electrophoresis. (C) 2001 Elsevier Science B.V. All righ ts reserved.