. . "lent bond with the dye moiety and P is H or a leaving group such as halide or sulfonate. [0167] Synthesis of terminal-phosphate-labeled nucleoside-5???-tetraphosphates: [0168] wherein X is NH, O, S, or CH2, [0169] Y is NH, O, S, ONH, CO, CH2 or another functional group capable of forming a covalent bond with the dye moiety and P is H or a leaving group such as halide or sulfonate. [0170] Synthesis" . .