Efficient photoaffinity labeling of human beta-hexosaminidase A. Synthesis and application of 3-azi-1-[(2-acetamido-2-deoxy-1-beta- D-glucopyranosyl)thio]- and -galactopyranosyl)thio]butane.

Two photolabile thioglycosides (8 and 9) were synthesized by Koenigs-Knorr type glycosylation. These compounds, being enzyme-resistant analogues of N-acetylhexosaminides, were shown to be good competitive inhibitors of lysosomal beta-hexosaminidase (2-acetamido-2-deoxy- beta-D-hexoside acetamidodeoxyhexohydrolase, EC 3.2.1.52) action. For photoaffinity labeling 3H-labeled 8a was prepared by enzymatic oxidation with galactose oxidase followed by reduction with sodium [3H]borohydride. Compound 8a, when photolyzed in the presence of hexosaminidase, specifically labeled both subunits of the enzyme.