| abstract |
Fluorescent labels are provided employing energy absorber/donor components and energy acceptor/fluorescer components joined together by a spacer which comprises sugar phosphate monomeric units, particularly ribosyl phosphate monomeric units, where the sugar groups are free of active hydroxyl groups. Particularly, an energy transfer component is substituted at the 5' position of the spacer chain, while the other energy transfer component is substituted at the 1' position of the 3' terminal ribosyl group of the label forming an ET cassette for linking to a nucleic acid sequence with any compositions. By employing combinations of ET components, with a common energy absorber/donor and different fluorescers, one can provide for families of labels which can be tagged to any target molecules and which can be excited at a single wavelength and fluoresce at different wavelengths with large Stokes shifts. The compositions find particular application in sequencing. |