4-MUG Trihydrate

4-MUG (4-Methylumbelliferyl-b-D-glucuronide) is a fluorescent substrate for b-D-Glucuronidase (GUS) encoded by the gusA gene isolated originally from E.coli. Cleavage of the substrate 4-MUG by a b-glucuronidase activity leads to the generation of the fluorigenic product 4-MU, which can be visualized or detected by irradiation with UV light. The fluorescence assay allows quantitation of GUS activity by means of a fluorimeter in protein extracts in conjunction with 4-MUG at a peak excitation of 365nm (UV) and a peak emission of 455nm (blue).