Toward a mechanism-based fluorescent assay for site-specific recombinases and topoisomerases: assay design and syntheses of fluorescent substrates

Oligonucleotides with a number of unique 3'-phosphoryl substituents were synthesized. Findings indicated that oligonucleotides with a 3'-phosphoryltyrosine residue N-substituted on tyrosine with the bulky fluorescent groups dansyl and pyrene are ligated effectively by the FLP recombinase and the dansyltyrosine derivative is utilized effectively as the tyrosine adduct by mammalian topoisomerase I.