Degradation of keratan sulfate by beta-N-acetylhexosaminidases in GM2-gangliosidosis.

We have prepared a new substrate from a keratan sulfate-derived-oligosaccharide (2-acetamido-2-deoxyglucosyl-(1--3)-[1-3H] Galactitol), which is necessary to measure beta-N-acetylhexosaminidase activity. This substrate was prepared from a cornea keratan sulfate by digestion with endo-beta-galactosidase, followed by isolation of disaccharide on gel filtration chromatography and chemical desulfation. Using this substrate, we found that a striking deficiency of beta-N-acetylhexosaminidase activity was present in the skin fibroblasts of patients with Sandhoff disease but not in Tay-Sachs disease. Both beta-N-acetyl-hexosaminidase A & H contributed to the catabolism of keratan sulfate.