A Study on the Interaction of Alizarin Red with Calf Thymus DNA: Fluorescence Enhancement Technique

The interaction of Alizarin Red (Sodium salt of 2, 3-dihydroxy-9, 10-anthraquinone-3-sulfonic acid), chromophore with calf thymus DNA (ct DNA) was investigated by fluorescence enhancement technique. Alizarin Red-DNA solution gave an emission spectrum in the wavelength range 500 - 650 nm, when excited at 515 nm. The magnitude of fluorescence intensity increased on increasing the complex ratio, R ([DNA/Az-R]). This fluorescence enhancement was used to calculate the binding parameters (the binding constant and the binding sites) for the Alizarin Red – DNA interaction. The binding constant value was found to be 3.0 × 10⁴ M⁻¹ and the binding capacity (sites) was 3. The results suggest that the technique of fluorescence enhancement can be used successfully to study the interaction