Activity of chondroitin ABC lyase on dermatan sulfate partially degraded by cupric-ion-mediated free-radical treatment.
Dermatan sulfate was extracted and purified from bovine intestinal mucosa, pig intestinal mucosa and pigskin. Small differences in M(r), charge density and constituent disaccharides were detected for the three purified natural dermatan sulfates. Bovine intestinal mucosa dermatan sulfate was depolymerized by a controlled free-radical process mediated by cupric ions in the presence of hydrogen peroxide. Different low-molecular-mass dermatan sulfate fractions were produced and analysed by high-performance size-exclusion chromatography and polyacrylamide gel electrophoresis. The results obtained by this last technique strongly support the hypothesis that the free-radical process proceeds essentially via the destruction of disaccharide units. The partial degradation of dermatan sulfates by cupric-ion-mediated free-radical treatment reduces or even eliminates the capacity of chondroitin ABC lyase to depolymerize these derivatives. This was confirmed by polyacrylamide gel electrophoresis and the time curves of enzymatic treatments evaluated by spectrophotometry.