Figure 9. Fluorescence-monitored titration of M-chelate-Rev catalysts with added supercoiled plasmid DNA (4). A, Fluorescence emission of the internal Trp residue of Ni-KGHK-Rev, both before and after the addition of plasmid DNA, illustrating the blue shift in Trp fluorescence that occurred upon binding of Ni-KGHK-Rev to DNA. B, Titrations were monitored by following the decrease in the ratio of fluorescence intensities at 362 nm and 328 nm, resulting from the blue shift in Trp fluorescence emission that occurred upon binding to DNA. Control experiments lacking DNA did not provide a response.