Book of Abstracts: Albany 2007
June 19-23 2007
Finding AT-DNA ? Kinetic Recognition of Long Adenine-Thymine Stretches by Metal-Ligand Complexes
Threading of bulky binuclear ruthenium(II) complexes in or out of the base stack in DNA is an extremely slow process that requires a considerable conformational change of the double helix. The rate of intercalation is highly sensitive to the structure and stereochemistry of the metal-ligand coordination and, in particular, to the base sequence around the intercalation site: 2500 times faster with poly(dAdT)2 compared to mixed-sequence DNA for the most selective complex. Studies with oligonucleotides having a central AT-tract of varying length demonstrate that at least one complete helix turn of AT basepairs is necessary for efficient threading, indicating that the transition state involves a stretch of DNA considerably larger than the dimensions of the complex itself. Our results demonstrate that this "kinetic recognition", in which the selection mechanisms go beyond the short-range interactions of a simple lock and key model, can provide a highly sequence-selective DNA interaction.
References and Footnotes
Department of Chemical and Biological Engineering/Physical Chemistry