A fluorescent assay for proteolytic enzymes

Abstract

A method is described which permits the assay of proteolytic enzyme activity on protein substrates without precipitation or filtration steps, utilizing a fluorescent reagent which is specific for primary amines. The assay is about 100 times more sensitive than the Lowry method, much faster and less complicated. Ambiguities concerning the absorbing species are largely eliminated. The reagent (Fluorescamine, Hoffmann-La Roche RO-20-7234) yields fluorescent compounds with amino acids at pH 9.0 and with peptides at pH 6.8, but possesses no fluorescence by itself.