Probing interactions of antimony species with DNA by short column capillary electrophoresis coupled with inductively coupled plasma mass spectrometry

Abstract

The interaction of two inorganic antimony species (Sb^III and Sb^V) with Herring fish DNA was studied by short column capillary electrophoresis (SC-CE) coupled with inductively coupled plasma mass spectrometry (ICP-MS). No Sb^V-DNA interaction was observed under simulated physiological conditions. The thermodynamic and kinetic parameters for the interaction between Sb^III and DNA were determined by the SC-CE-ICP-MS assay. The stoichiometry for the interaction of Sb^III with DNA was 1 : 1. The binding constant for the Sb^III-DNA interaction was (1.36 ± 0.07)×10⁶ L mol⁻¹, showing strong affinity of Sb^III to DNA under physiological condition. The interaction of Sb^III with DNA was exothermic and thermodynamically favorable, both enthalpically and entropically driven. The ΔH, ΔS and ΔG values were –(8.30 ± 0.44) kJ mol⁻¹, 90.6 ± 1.5 J mol⁻¹ K⁻¹, and –(28.1 ± 0.6) kJ mol⁻¹, respectively. The binding of Sb^III to DNA followed a first-order kinetics for Sb ^III and a zero-order kinetics for DNA with a reaction rate constant of (2.7 ± 0.1) × 10⁻³ h⁻¹ at 37 °C and an apparent activation energy (E_a) of 194 ± 11 kJ mol⁻¹.