DNA polymerase I (holoenzyme and Klenow fragment),
Taq DNA polymerase
reverse transcriptase (e.g., from AMV and M-MuLV).
Fluorescein-12-dUTP has been used to label nuclear extracts during PCR. It has also been used to replace dTTP in the random-primed DNA labeling reaction or in nick translation reactions, as well as in PCR. The nucleotide also serves as a substrate for terminal transferase in 3′-end labeling and TUNEL. Fluorescein-labeled probes can be used for in in situ hybridization with direct fluorescence detection or detection by enzyme linked immunoimmunsorbent assay (ELISA) using Anti-Fluorescein-AP, Fab fragments. Repeated fluorescence labeling using Tetramethyl-Rhodamine-6-dUTP (red) and AMCA-6-dUTP (bright blue) is possible.