CPF4

FRET (fluorescence resonance energy transfer) is a radiationless transmission of an energy quantum between two fluorophores in close proximity. Cleaving of the chemical bond between these fluorophores, which have an overlap in their spectra, results in a large shift in the emission spectra. Addition of a Phosphodiesterase I, which catalyzes the hydrolysis of phosphodiester bonds (substrates are nucleic acids and cyclic nucleotides) to an aqueous solution of CPF4 results in an increase in the donor fluorescence and a decrease in the acceptor fluorescence. CPF4 is an effective tool to monitor the activity of phosphodiesterases in real time with high sensitivity.