Analysis of binding affinity of biologically active material spiro-pyrimidine and DNA: a spectroscopic approach

Abstract

ABSTRACTThe binding phenomena of spiro-pyrimidine (SP) and calf thymus DNA (CTDNA) were studied using spectroscopy. Apparent association constant (1.81 × 104 L/mol), as calculated from UV–vis spectra, indicates a moderate complex formation between CTDNA and SP. The quenching of emission spectra of ethidium bromide–CTDNA by SP was observed, and it is the static type. The binding constants for this interaction found to be 14.12, 3.39 and 1.32 × 102 L/mol at 293, 303 and 313 K. Thermodynamic parameter, enthalpy change (ΔH) and entropy change (ΔS), designate weak force like van der Walls force and hydrogen bonds having the crucial role in this binding process. The results of circular dichroism demonstrate that SP has not induced characteristic changed in CTDNA. The obtained spectroscopic results indicating the binding mode of SP with DNA seem to be a non-intercalative binding.