Patent ID: 7595162

Claim:
A method of forming a fluorescently labeled polynucleotide, comprising the step of enzymatically extending a primer in the presence of a template polynucleotide and a mixture of nucleotides comprising nucleotides suitable for effecting template-dependent primer extension, wherein at least one nucleotide of the mixture is labeled with an energy transfer dye which comprises: (i) a xanthene donor dye capable of absorbing light at a first wavelength and emitting excitation energy in response thereto; (ii) a 4,7-dichlororhodamine acceptor dye capable of absorbing the excitation energy emitted by the donor dye and fluorescing at a second wavelength in response thereto; and (iii) a non-nucleosidic linker linking the xanthene donor dye to the 4,7-dichlororhodamine acceptor dye.