Unravelling the binding mechanism of a poly(cationic) anthracenyl fluorescent probe with high affinity towards ds-DNA

By Marco Deiana, Bastien Mettra, Katarzyna Matczyszyn, Delphine Pitrat, Joanna Olesiak-Banska, Cyrille Monnereau, Chantal Andraud, Marek Samoc

July 28, 2017

  • Year

  • Technique

  • Industry

Title

Unravelling the binding mechanism of a poly(cationic) anthracenyl fluorescent probe with high affinity towards ds-DNA

Author

Marco Deiana, Bastien Mettra, Katarzyna Matczyszyn, Delphine Pitrat, Joanna Olesiak-Banska, Cyrille Monnereau, Chantal Andraud, Marek Samoc

Year

2016

Journal

Biomacromolecules

Abstract

We report the synthesis, spectroscopy, and the DNA binding properties of a biocompatible, water-soluble, polycationic two-photon absorbing anthracenyl derivative (Ant-PIm) specifically designed for bio-related applications. Detailed insights into the Ant-PIm-DNA binding interaction are provided by using several spectroscopic approaches, including UV-VIS absorption, circular dichroism (CD), Fourier-transform infrared spectroscopy (FTIR), steady-state and time-resolved fluorescence techniques. Absorption and fluorescence quantitative data analysis show a strong Ant-PIm-duplex interaction with binding constants of: Kf = 4.7 ± 0.2 × 105 M-1, 7.1 ± 0.3 × 105 M-1 and 1.0 ± 0.1 × 106 M-1 at 298, 304 and 310 K, respectively. Spectral changes observed upon DNA binding provide evidence for a complex formation with off-on fluorescence pattern, which can be related to two consecutive binding equilibria. Results of DNA binders displacement and iodide quenching experimental assays unambiguously point to the groove binding mode of Ant-PIm to the DNA-helicate. Thermodynamic and chemical denaturation studies suggest that long-range interactions of hydrophobic nature regulate the association of Ant-PIm with the biopolymer. The ionic strength dependence of the binding constant shows that electrostatic component has an important contribution to the overall Gibbs free energy. FTIR and CD data provide evidence of partial modification of the B-DNA secondary structure, while the increase in the melting temperature clearly indicates the enhancement of the thermal stability of the duplex. Furthermore, the two-photon absorption cross section spectrum determined using the TPEF technique shows a strong 2PA maximum at 820 nm with a σ2 ˃ 800 GM which emphasizes the advantageous combination of biological and optical properties possessed by this positively charged bio-probe.

Full Article

http://pubs.acs.org/doi/abs/10.1021/acs.biomac.6b01113

Instrument

J-815

Keywords

Circular dichroism, DNA structure, Thermal stability, Biochemistry