Cooperative Oligonucleotide-Directed Triple Helix Formation at Adjacent DNA Sites

Natalia Colocci, Mark D. Distefano, Peter B. Dervan

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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 languageEnglish (US)
Pages (from-to)4468-4473
Number of pages6
JournalJournal of the American Chemical Society
Issue number11
StatePublished - May 1 1993


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