Patent ID: 6855503

Claim:
An energy transfer dye labeled cassette of the formula: wherein D is a donor dye selected from the group consisting of xanthine dyes, rhodamine dyes, and cyanine dyes; L 1 is a functional group selected from the group consisting of C 1 -C 20 alkynyl-amine, alkynol, alkenamine, alkylamine, keto, and thiol, through which D is covalently attached; R 1 , R 2 , R 3 and R 4 independently represent H, alkyl, halo, hydroxy, thio, nitro, amino or alkylamino groups; L 2 is an amine selected from the group consisting of C 1 -C 2 alkynylamine, alkynol, alkenamine, alkylamine, keto, and thiol, through which A is covalently attached; X is an aldehyde, an acid, an acid chloride, an ester, hydroxymethyl, CH 2 O-mesylate, CH 2 O-triflate, mercaptomethylene, phosphoramidite or other reactive groups capable of forming a covalent bond with amine, thiol, hydroxy, or haloacetyl containing biological molecules; A is an acceptor dye selected from the group consisting of xanthine dyes, rhodamine dyes and cyanine dyes; and wherein the positions of A and D are interchangeable.