The changes in binding free energies due to cooperativity for oligodeoxyribonucleotides bound to adjacent sites by triple helix formation have been determined by quantitative affinity cleavage titrations. A 20-fold enhancement in equilibrium association constant is realized for an 11 mer pyrimidine oligonucleotide binding in the presence of a neighboring bound site at 24 °C and pH 7.0 (25 mM Tris-OAc, 10 mM NaCl, 1 mM spermine). This corresponds to an increase in binding free energy of 1.8 ± 0.2 kcal mol−1. This cooperativity is not observed when the two binding sites are separated by one base pair.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of the American Chemical Society|
|State||Published - May 1 1993|