4-Methylumbelliferyl butyrate

4-Methylumbelliferyl butyrate (4-MUB) is a fluorogenic coumarin derivative used to detect Moraxella catarrhalis C4-esterase activity. Upon enzymatic hydrolysis, it yields the fluorescent product 4-methylumbelliferone (4-MU), making it a key tool for in vitro enzymatic assays and microbiological research.