engleski

Molecular Recognition of ds-DNA/RNA Secondary Structure by Self-Assembled Enantiomeric Perylene Bisimide Chromophores

Dedicated efforts have been made in the last decade towards recognition of nucleic acids mainly by small cationic chromophores. In recent years, aromatic chromophores with extended hydrophobic surfaces, in particular self-assembling perylene bisimides (PBIs), have been used for the investigation of covalently bound DNA-PBI conjugates and - interactions of PBIs with G- quadruplex DNA. However, study of non-covalent interactions of PBI chromophores with double- stranded (ds)-DNA/RNA is rather scarce. To further explore this interesting research area we have synthesized a series of four enantiomeric pairs of amino acid appended perylene bisimides (L, L/D, D- 1, L, L/D, D-2, L, L, L/D, D-3 and L, L/D, D-4) and studied their interactions with (ds)-DNA/RNA by UV/Vis, fluorescence and circular dichroism (CD) spectroscopy. These water-soluble homochiral PBIs form helical self-assemblies with high binding constants and they can be stabilized by addition of salts (buffer and/or sodium chloride). The interaction of enantiomeric PBls with (ds)- DNA/RNA at dilute concentration leads to strong stabilization of such nucleotides against thermal denaturation. More interestingly, induced circular dichroism (ICD) of PBI assemblies created within DNA/RNA grooves was observed. These ICDs profiles are strongly dependent on the steric features of the substituents (R) at chiral center of amino acid units in PBIs and secondary structures of DNA or RNA. These observations could be explained in terms of excitonically coupled PBI dimers into the DNA/RNA grooves. Our detailed results on the interaction of enantiomeric PBIs with (ds)-DNA/RNA will be presented in our poster.

molecular recognition ; ds DNA/RNA ; perylene bisimide

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