Liberation of N-acetylglucosamine-6-sulfate by human beta-N-acetylhexosaminidase A.
The first step of the degradation of p-nitrophenyl-6-sulfo-2-acetamido-2-deoxy-beta-D-glucopyranoside and of keratan sulfate-derived oligosaccharides bearing N-acetylglucosamine-6-sulfate residues at the nonreducing end was considered to be accomplished by the action of a specific sulfatase (Kresse, H., Paschke, E., von Figura, K., Gilberg, W., and Fuchs W. (1980) Proc. Natl. Acad. Sci. U. S. A. 77, 6822-6826). In purification from human placenta, however, this activity co-chromatographed with isoenzyme A of beta-N-acetylhexosaminidase and had the same electrophoretic mobility as the latter enzyme. The activity was precipitated by a specific antiserum against beta-N-acetylhexosaminidase. A pronounced enzyme deficiency was found in Tay-Sachs and Sandhoff fibroblasts. The purified enzyme released p-nitrophenol from the chromogenic substrate as well as a second product which contained equimolar amounts of hexosamine and sulfate. This product had the same electrophoretic and chromatographic behavior as sulfated N-acetylglucosamine. It could be degraded by periodate to a smaller charged fragment. Incubation of keratan sulfate-derived oligosaccharides with beta-N-acetylhexosaminidase A analogously resulted in the liberation of N-acetylglucosamine-6-sulfate. The enzyme showed the highest affinity towards a trisulfated tetrasaccharide and exhibited a similar Km for the sulfated and the unsulfated p-nitrophenyl derivative.
D000117:Acetylglucosamine / Q000031:analogs & derivatives* / Q000302:isolation & purification; D002478:Cells, Cultured; D005347:Fibroblasts / Q000201:enzymology; D005944:Glucosamine / Q000031:analogs & derivatives*; D006596:Hexosaminidases / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D009083:Mucopolysaccharidoses / Q000201:enzymology; D012497:Sandhoff Disease / Q000201:enzymology; D012867:Skin / Q000201:enzymology; D013379:Substrate Specificity; D013462:Sulfur Radioisotopes; D013661:Tay-Sachs Disease / Q000201:enzymology; D014316:Tritium; D001619:beta-N-Acetylhexosaminidases
D013462:Sulfur Radioisotopes; D014316:Tritium; C033137:N-acetylglucosamine-6-sulfate; D006596:Hexosaminidases; D001619:beta-N-Acetylhexosaminidases; D005944:Glucosamine; D000117:Acetylglucosamine