Square wave voltammetric and computational studies of thyroxine –thiourea interaction

The voltammetric behavior of Thyroxine (T4) was studied using square wave voltammetry in phosphate buffer solution at (pH 7.0) as supporting electrolyte. Thyroxine gives two well-defined reduction peaks at Ep1 (-0.359) volt and Ep2 (-1.01) volt versus the reference electrode (Ag/AgCl/Sat. KCl). The calibration curve is linear within a two range of concentration, first is (1.996 x10-7-19.61 x10-7) M with the R2 equal to (0.999) and (0.9963) for Ep1 and Ep2 respectively, and second (0.996 x10-6-11.857 x10-6) M with the R2 equal to (0.9819) and (0.9848) for Ep1 and Ep2 respectively. The Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) changes of temperature dependent on (K) were calculated using Vant Hoff equation for Thyroxine and Thiourea binding. The molecular docking between Thyroxine and Thioureahas been studied, and the results indicates thatthe interaction between T4 and TU was mainly hydrogen bonding and van der Waals interaction