Khalfan H, Abuknesha R, Robinson D
Biochem J. 1983 Jan 1;209(1):265-7. doi: 10.1042/bj2090265.
A method for the preparation of casein labelled with the 4-methylumbelliferyl fluorophore is described, and the product was used as a fluorigenic macromolecular substrate for a sensitive assay of the activity of proteinases. Nanogram quantities of trypsin, chymotrypsin, elastase and cathepsin D can be detected, but the substrate is unaffected by cathepsin B.