Fluorogenic substrates for proteases based on intramolecular fluorescence energy transfer (IFETS)

A prospective class of intramolecular fluorescence energy transfer substrates (IFETS) is described. In contrast to the known chromogenic and fluorogenic substrates that are used widely in the scientific and medical research, IFETS allow to control the enzymatic cleavage at any point of the peptide chain and thus permit simultaneous studies of enzymes of different specificity. We discuss the main types of donor and acceptor, their advantages and drawbacks and the effectiveness of exited-state energy transfer between them. High sensitivity and selectivity of IFETS in the assay of proteinases was demonstrated. They prove to be a very useful and very promising instrument for enzymology and medicine.