The tetrameric lysosomal enzyme beta-glucuronidase hydrolyses glucuronate from the HA tetrasaccharide (Oshima et al. 1987) resulting in the single sugars glucuronic acid and N-acetylglucosamine. These single sugars can exit the lysosome by an unknown mechanism. L-aspartic acid is an inhibitor of enzyme activity (Kreamer et al. 2001).