Luminescence Quenching as a Probe of DNA Binding Mode

Résumé du livre

Abstract: The oxidative luminescence quenching [Ru(phen)3]2 (phen = 1,10- phenanthroline) and [Ru(diMe-phen))3]2] (diMe-phen = 4,7-dimethyl-1,10- phenanthroline) by 1,4-naphthoquinone (NQ) and 2-methyl-i,4-naphthoquinone (2-Me- NQ) was investigated in the absence and presence of calf thymus DNA. DNA binding studies show that NQ, with a DNA binding constant, K(b), of 1.7 x 105 M−1, intercalates between the DNA bases, while 2-Me-NQ, with K(b) = 8.2 x 104 M−1, may partially intercalate. Relative viscosity experiments were performed comparing NQ and 2-Me-NQ to known DNA binders. The addition of NQ to DNA solutions increases the viscosity, confirming that it intercalates between the DNA bases. In the case of 2-Me- NQ, the relative viscosity plot is consistent with partial intercalation. Luminescence intensity and lifetime quenching studies of [Ru(phen))3]2 and [Ru(diMe-phen))3]2+ were performed in water using NQ and 2-Me-NQ as the quenchers. The plot of I0/I and [tau]0/[tau] as a function of quencher concentration, NQ and 2-Me-NQ, for [Ru(phen))3]2+ in H2O, shows that both curves overlay, consistent with a dynamic quenching mechanism. For [Ru(diMe-phen)3]2+ the Stern-Volmer plot of the quenching by NQ showed dynamic quenching at [NQ]