CAPILLARY ELECTROPHORESIS OF GLYCOSAMINOGLYCAN-DERIVED DISACCHARIDES - APPLICATION TO STABILITY STUDIES OF GLYCOSAMINOGLYCAN CHITOSAN COMPLEXES

Capillary zone electrophoresis (CZE) was used to separate the disaccha rides produced by chondroitinase digestion of chondroitin sulfates. Th e main disaccharides formed upon depolymerization have identical charg e and mass. Baseline resolution of these two compounds was achieved by selecting appropriate concentration and pH of a berate buffer. Valida tion of the method showed a good linearity of the response and a very satisfactory reproducibility of migration times with a relative standa rd deviation (RSD) of less than 0.4%. The reproducibility of peak area s was improved by using an internal standardization. The addition of c innamic acid (internal standard) to the incubation medium allowed us t o perform kinetic measurements of the depolymerization while keeping a baseline resolution of the two main disaccharides analyzed during the complete digestion course even when their concentration in the incuba tion medium increased. Application of this method to the comparison of the rate of hydrolysis of chondroitin sulfate and of a complex associ ating chondroitin sulfate with chitosan showed clearly that, at the ph ysiological pH, chitosan protected the chondroitin sulfate from depoly merization. This phenomenon was more pronounced as the pH of the incub ation medium was far from the optimum pH activity of the chondroitinas e.