STUDIES ON IONIC INTERACTIONS BETWEEN A GLYCOSAMINOGLYCAN CHONDROITIN-6-SULFATE AND LYSINE-CONTAINING POLYPEPTIDES BY NMR-SPECTROSCOPY

The interactions between chondroitin-6-sulfate (COS) and lysine deriva tives such as oligolysines, polylysines (PL), and copolylysines were e xamined to elucidate functions of bioactive sulfated glycosaminoglycan s by means of NMR spectroscopy. Gellike complexes were obtained by the ionic interactions of sulfate and carboxyl anions of COS with ammoniu m cations of lysine derivatives having molecular weights more than 771 Da. NMR spectra revealed that the gellike complex was formed by the r eaction between the two starting materials. The proportion of the gell ike complex changed with pH. molar ratio, concentration, and molecular weight of polylysine. Maximum amount of the gellike complex was attai ned in a combination of COS with polylysine or hydrophilic copolylysin e in the ionic ratio of 1.0. Molecular motions of saccharide and polyl ysine backbone in the gellike complex were affected by the degree of c ross-linking and the extent of ionic interactions.