ABSTRACT
We report here the details of G4-FID (G-quadruplex fluorescent intercalator displacement), a simple method aiming at evaluating quadruplex-DNA binding affinity and quadruplex- over duplex-DNA selectivity of putative ligands. This assay is based on the loss of fluorescence upon displacement of thiazole orange from quadruplex- and duplex-DNA matrices. The original protocol was tested using various quadruplex- and duplex-DNA targets, and with a wide panel of G-quadruplex ligands belonging to different families (i.e. from quinacridines to metallo-organic ligands) likely to display various binding modes. The reliability of the assay is further supported by comparisons with FRET-melting and ESI-MS assays.
Subject(s)
DNA/chemistry , DNA/metabolism , G-Quadruplexes , Acridines/chemistry , Acridines/metabolism , Base Sequence , Benzothiazoles/metabolism , DNA/genetics , Ligands , Oligonucleotides/chemistry , Oligonucleotides/genetics , Oligonucleotides/metabolism , Organometallic Compounds/metabolism , Quinolines/metabolism , Quinolinium Compounds/metabolism , Salts/pharmacology , Sensitivity and Specificity , Time FactorsABSTRACT
Fluorimetric titrations were performed to gain insight into parameters that govern the association of thiazole orange (TO) and G-quadruplex-DNA (G4-DNA). Use of loop-containing and loop-lacking quadruplexes evidenced the critical influence of the loops on the stoichiometry of the association and on the fluorescence exaltation of TO. We subsequently tried to benefit from this sensitivity to evaluate the influence of G4-DNA cationic environment on ligand binding via a recently reported G4-FID assay.
Subject(s)
Benzothiazoles/chemistry , DNA/chemistry , Fluorescent Dyes/chemistry , G-Quadruplexes , Quinolines/chemistry , Spectrometry, Fluorescence/methods , Fluorescence , LigandsABSTRACT
[structure in text] Aromatic ortho-disulfone derivatives are readily accessible from diiodide precursors by Cu(I)-mediated reactions with sodium sulfinate salts. The sulfone substituents adopt C(2)-symmetric enantiomeric conformations (lambda and delta) as evidenced by X-ray structural analysis and (1)H and (31)P NMR on chiral bis(sulfonyl)veratrol derivatives and hexacoordinated tris(benzenediolato)phosphate anions. Slow dynamic conformational isomerism (DeltaG(++) > or = 19.8 kcal mol(-1)) was detected in solution.
ABSTRACT
Chiral TRISPHAT anions behave as efficient asymmetric hosts controlling with high efficiency the configuration of a cationic dicobalt(II) triple helicate--de up to 82%.
