Methylumbelliferyl glycosides

The synthesis of a 4-methylumbelliferyl glycoside of A-acetyl-a-D-neuraminic acid has been reported for use as a substrate for the fluorometric detection and estimation of a-neuraminidase. ... 

Methylumbelliferyl tri-JV-acetyl-j8-chitotrioside is a convenient substrate for the assay of lysozyme, since the 4-methylumbelliferone formed can be measured by the increased fluorescence at 442 nm. The binding constant and rate of hydrolysis of this trioside were higher than those of 4-nitrophenyl tri-iV-acetyl-/5-chitotrioside. 4-Methylumbelliferyl glycosides of 2-acetamido-2-deoxy-j8-D-glucopyranose and di-A acetyl-jS-chitobiose were also investigated as substrates. 

Hydrolysis of 4-Methylumbelliferyl D-Glycosides by D-Glucosidase A from Almonds and by / D-Glucosidase Aj from Aspergillus wentiP ... 

To detect the fate of liposomes, the nonfluorescent 4-methylumbelliferyl-p-D-glycoside [4MU-(3-D-glc)] can be encapsulated. 4MU-(3-o-glc) is a substrate for lysosomal 3-d-glycosidase that shows fluorescence after enzymatic hydrolysis to methylumbelliferone (125). 

Binding Experiments. Some of these chromophoric glycosides proved also to be valuable in cases where no hydrolysis by the cellulases occurred. This was shown in the case where the 4-methylumbelliferyl glucoside and cellobioside were not hydrolyzed by the CBH II from Trichoderma (see above) but could be used as reporter ligands in a series of binding experiments. Typically the fluorescence of the cellobioside was quenched in the presence of CBH II and was restored by the addition of excess amounts of non-chromophoric ligands, i.e., cellobiose (Fig. 3). Thus association constants... 

Table 1. Differentiation of Cellulolytic Enzymes According to their Substrate Specificities using Covalently Dyed Hydroxyethyl-cellulose (OBR-HEC) and xylan (RBB-X) and 4-methylumbelliferyl 3-glycosides as Substrates. For abbreviations see the text.

A method for the assay of a-L-fucosidase has been based on the use of 4-methylumbelliferyl a-L-fucopyranoside this substrate was hydrolysed more readily than the corresponding 4-nitrophenyl glycoside by human-liver a-L-fucosidase, where human-serum a-L-fucosidase showed approximately the same activity towards both substrates. The pH-activity profiles of the enzyme are similar for both substrates, and both isoenzymes of human a-L-fucosidase are active against these substrates. The greater sensitivity of the fluorescence method enhances its use in the diagnosis of fucosidosis (mucopolysaccharidosis F). 

Kleineidam, R. G., Furuhata, K., Ogura, H., and Schauer, R., 1990, 4-Methylumbelliferyl-a-glycosides of partially 0-acetylated N-acetylneuraminic acids as substrates of bacterial and viral sialidases, Biol. Chem. Hoppe-Seyler yi l 5-l 9. 

---