The Thermodynamic Effects of Ligand Structure on the Molecular Recognition of Mononuclear Ruthenium Polypyridyl Complexes with B‐DNA

Autor: Frederick M. MacDonnell, Jake C. White, Logan R. Martin, Nagham Alatrash, Edwin A. Lewis, Venkata R. Machha, Jesse I. DuPont, Clinton G. Mikek
Rok vydání: 2017
Předmět:
Zdroj: European Journal of Inorganic Chemistry. 2017:3604-3611
ISSN: 1099-0682
1434-1948
Popis: ITC, CD, and ESI-MS techniques were used to study the thermodynamics of RPC*DNA complex formation for binding three different RPCs to duplex DNA. RPCs were [Ru(phen)₃]2+ (1), [Ru(phen)₂(dppz)]2+ (2), and [Ru(phen)₂(tatpp)]2+ (3). We examined the binding of enatiomerically pure Δ-RPC and Λ-RPC isomers as well as racemic RPC mixtures to B-DNA. RPC*B-DNA binding is characterized by a combination of groove binding and intercalation, with the thermodynamics being similar for binding both the enantiomerically pure compounds and the racemic mixtures. The ΔG values for RPC*DNA complex formation range from -5.6 to -9.1 kcal/mol. In all cases, complex formation is driven by a favorable change in entropy with values for -TΔS ranging from -7.3 to -14.0 kcal/mol. To better understand the intercalation versus groove binding contributions to the overall binding energy we compared the thermodynamics for formation of the 1, 2, and 3 DNA complexes to the thermodynamics for formation of the [Ru(phen)₂(tatpp)Ru(phen)₂]4+ (4) DNA complex. The RPC DNA binding affinities follow the trend: 1< 4 < 2 < 3. Differences in the affinity for binding 1 versus 2 or 3 are almost entirely due to the size of the intercalating moiety, e.g. phen vs. dppz or tatpp. The lower affinity for 4 (containing the tatpp bridge) is due to the solvation penalty for the second Ru core complex that extends out from the major groove.
Databáze: OpenAIRE
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