Soluble, dye-labelled substrates for a micro-plate assay of proteinase activity

Gelatin, collagen and casein derivatives were covalently linked with Remazol Brilliant Blue R (RBB). New dye-labelled, soluble substrates were obtained, suitable for the detection and assay of proteinase activity. A reliable colorimetric micro-plate assay was designed, based on the precipitability of gelatin-RBB, collagen-RBB and casein-RBB from buffered solutions with hydrochloric acid. Additionally, a sensitive plate-clearing assay was developed for the detection and isolation of proteolytic microorganisms from mixed populations, or for the screening of pure cultures.