Simultaneous determination of the association constants of oligosaccharides to a lectin by capillary electrophoresis

The association constants (K-a values) of oligosaccharides as 8-amino-1,3,6 -naphthalenetrisulfonate (ANTS) or 1-phenyl-3-methyl-5-pyrazolone (PMP) der ivatives to lectins were determined in the reverse (an oligosaccharide deri vative as sample and a lectin as additive) system by electrophoresis in a c apillary coated with linear polyacrylamide. The determination was as reliab le as in the direct (a lectin as sample and an oligosaccharide derivative a s additive) system by electrophoresis in a capillary base fused silica. The reverse system had the advantage that the K-a values of multiple oligosacc harides could be determined simultaneously. Thus, the K-a values of lactose and melibiose (as PMP derivatives) to M-r 60 000 Ricinus communis agglutin in could simultaneously be determined by this method. The K-a values of a n umber of isomaltooligosaccharides (as ANTS derivatives) having various degr ees of polymerization (DPs) to M-r 46 000 Lens culinaris agglutinin could a lso be simultaneously determined. The K-a values gradually increased with D P, implying the participation of not only the non-reducing end but also the interior portion of the oligosaccharide chain. The K-a value of an oligosa ccharide obtained in the multiple solute reverse system was consistent with that obtained by the single solute reverse system, demonstrating the relia bility of this simultaneous determination. (C) 1999 Elsevier Science B.V. A ll rights reserved.