The distribution of sulphate residues in the chondroitin sulphate chain.

1. Electrophoresis of chondroitin sulphate, before and after partial degradation with testicular hyaluronidase, revealed charge heterogeneity of the degraded but not of the intact polymer. 2. Hyaluronidase-treated chondroitin sulphate was fractionated by gel chromatography. Two subfractions which were essentially monodisperse with regard to molecular weight (values of 8600 and 4800, respectively) were separated further by chromatography on Dowex 1. The resulting subfractions differed considerably with respect to their sulphate/disaccharide molar ratios. 3. Amino acid and neutral-sugar analyses of the Dowex 1 subfractions showed that the less sulphated fragments contained the carbohydrate-protein linkage region, whereas the high-sulphated fragments essentially lacked this constituent. It was concluded that chondroitin sulphate contains relatively less sulphate in the vicinity of the carbohydrate-protein linkage region than in the more peripheral portion of the polysaccharide chain.