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Published on: October 11, 2016
Three thymine/adenine binding modes of the ruthenium complex Λ-[Ru(TAP)2(dppz)]2+ to the G-quadruplex forming
Kane McQuaid1, James P Hall, Lena Baumgaertner
1Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK. c.j.cardin@reading.ac.uk.
Abstract:
Λ-[Ru(TAP)2(dppz)]2+ was crystallised with the G-quadruplex-forming heptamer d(TAGGGTT). Surprisingly, even though there are four unique binding sites, the complex is not in contact with any G-quartet surface. Two complexes stabilise cavities formed from terminal T·A and T·T mismatched pairs. A third shows kinking by a TAP ligand between T·T linkages, while the fourth shows sandwiching of a dppz ligand between a T·A/T·A quadruplex and a T·T mismatch, stabilised by an additional T·A base pair stacking interaction on a TAP surface. Overall, the structure shows an unexpected affinity for thymine, and suggests models for G-quadruplex loop binding.
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