Fig. 1.

Glycosaminoglycan catabolism. The schemes show the different enzymatic activities required for the sequential catabolism of a hypothetical NREs from heparan sulfate, dermatan sulfate and keratan sulfate. It should be noted that the glucuronic acid 2-O-sulfatase in heparan sulfate degradation has been demonstrated in vitro, but has not yet been identified genetically.

Scheme modified from [3] according to findings from Lawrence et al. [18] and Kowalewski et al. [87].