heparitinase digestion of the proteoglycan reduced its mr to 143,000 , consistent with the removal of its four glycosaminoglycan chains with the exception of short segments adjacent to the carbohydrate-protein linkage region , whereas nitrous acid treatment brought about a smaller reduction in size ( to mr = 168,000 ) which was shown to be due to the resistance of the internal portion of the heparan sulfate polymer to this reagent .
C0017973
glycosaminoglycan
C0019143
heparan sulfate