Abstract
Relative to ligand-free duplex DNA, the melting temperature of the 1:1 complex of the duplex d(CGAATTGTATGC):d(GCATACAATTCG) with the conjugate of Hoechst 33258 with a des-metalloporphyrin, increased from 42 to 60.5°C indicating strong ligand binding. UV–vis spectrophotometric titration detected more than one class of binding site (apparent dissociation constants ∼0.2 μ M for simple noncooperative binding and 1 μ M for the simultaneous cooperative mode with Hill coefficient ∼2).
ACKNOWLEDGMENTS
We are grateful to the EU for a Marie-Curie Postdoctoral Fellowship (SF), to the BBSRC for support (EVB), and to Dr. Martin Baron for 400 MHz NMR access.