FLUORESCEIN-LABELED DNA PROBES FOR HOMOGENEOUS HYBRIDIZATION ASSAYS -APPLICATION TO DNA ESCHERICHIA-COLI RENATURATION

The sensitivity of the emission intensity of fluorescein to environmen tal changes opens the possibility for developing homogeneous DNA assay s. In this research, we were able to quickly and easily detect nucleic acid renaturation by using an E. coli DNA with approximately 4% conju gation of fluorescein to the N-4-aminoethyl-modified cytosine residues . We determined how the emission intensity of fluorescein attached to single-stranded DNA decreases when renatured to double-stranded DNA. T he decrease in fluorescence efficiency is due to changes in the fluore scein monoanion-dianion ratio because of pH modifications in the surro unding of the fluorescein label. The decrease in fluorescence intensit y was used for analysis of DNA E. coli renaturation kinetics.