Coumarin–fluorescein pair as a new donor–acceptor set for fluorescence energy transfer study of DNA

A method for introduction of the 2′-coumarin labeled nucleoside as a fluorescence energy donor into DNA duplexes has been described. Efficient FRET occurs between the coumarin–fluorescein pair in DNA owing to the high quantum yield of the donor. The present donor–acceptor pair may be useful as FRET indicator of DNA structures in solution.