Catalytic activity and structural changes of catalase in the presence of Levothyroxine and Isoxsuprine hydrochloride

Abstract

Two drugs that pregnant women (with hypothyroidism) may use during pregnancy include Isoxsuprine hydrochloride (ISO) and levothyroxine (LEV); ISO to reduce uterine contractions and LEV for the treatment of hypothyroidism. In the current work, we explored the mechanism of binding affinity between the above drugs and antioxidant enzyme Bovine Liver Catalase (BLC). The experimental results confirmed that both drugs could bind with BLC to form drug−BLC complexes but LEV showed a higher binding affinity toward enzyme. The binding constants of LEV–and ISO–BLC were 0.42 × 105 and 0.13 × 104 M−1 at 310 K, respectively. LEV enhanced the catalase activity but the enzymatic activity of BLC reduced gradually in the presence of ISO. Both drugs were able to induce conformational changes in the BLC structure. The results of the molecular docking investigations confirmed the experimental data and showed that the main binding forces in the LEV−BLC and ISO–BLC systems were hydrogen bond and hydrophobic force. The best binding site of both drugs on BLC is located at a cavity among the wrapping domain, N-Terminal arm, and β-barrel.