The use of glycosides of 6- and 8-acylamino-4-methylumbelliferone in studies of the specificity and properties of human lyosomal glycolipid hydrolases

Article abstract of DOI:10.1016/0008-6215(92)84111-5

A series of 6- and 8-acylamino-4-methylumbelliferyl β-D-galactopyranosides, β-D-glucopyranosides, and α-L-fucopyranosides having various fatty acyl residues were synthesized; 6- (9) and 8-hexadecanoylamino-4-methylumbelliferyl β-D-galactopyranoside (10) were shown to be substrates for human galactocerebrosidase.Analogs of 9 with shorter acid residues (octanoyl and butanoyl) were substrates for another type of β-D-galactosidase, i.e., G_M1-ganglioside-β-D-galactosidase.The specificity of various β-D-galactosidases for synthetic D-galactopyranosides, differing in the length and position of their acylamide residue, tested with enzyme preparations from patients with two types of glycolipidosis, Krabbe's disease (galactocerebrosidase and G_M1-β-galactosidase deficiency), suggested that 9 is a specific substrate for galactocerebrosidase in biochemical tests for Krabbe's disease.Fluorogenic 6-octanoyl- and 6-hexadecanoyl-amino-4-methylumbelliferyl β-D-glucopyranoside were much less readily hydrolyzed by both human and animal glucocerebrosidase than chromogenic 2-hexadecanoylamino-4-nitrophenyl β-D-glucopyranoside.Comparison of the hydrolysis of 4-methylumbelliferyl α-L-fucopyranoside with that of 6-hexadecanoylamino-4-methylumbelliferyl α-L-fucopyranoside by multiple forms of human α-L-fucosidase showed that the enzyme is capable of hydrolyzing not only hydrophilic but also synthetic, lipid-like substrates.