Fluorophore Used as a Donor of Fluorescence Resonance Energy Transfer (FRET)

Sodium 5-(2-aminoethylamino)-1-naphthalenesulfonate hydrate (EDANS, 1) is a fluorophore having a maximum excitation wavelength at 366 nm and a maximum emission wavelength at 490 nm. In a molecule processing 1 and DABCYL as a quencher having its maximum absorption wavelength at 470-520 nm, the fluorescent intensity of 1 decreases because of fluorescence resonance energy transfer (FRET). For example, when peptides bonding with 1 and DABCYL moieties are employed, FRET occurs to decrease the fluorescent intensity of 1. However the intensity returns by peptide-sequence-specific protease's cutting of peptides to release the DABSYL moiety. It has been reported that this method is applied to the assays of the human immunodeficiency virus (HIV) protease and the hepatitis C virus protease.^1,2)