Experimental and computational perspectives on the interaction of nerve agent VX metabolite ethyl methylphosphonic acid with human serum albumin

This study employed electrochemical methods to investigate the interaction between ethyl methylphosphonic acid (EMPA), the primary hydrolysis product of the nerve agent VX, and human serum albumin (HSA). Utilizing cyclic voltammetry (CV) and differential pulse voltammetry (DPV) on the surface of a glassy carbon electrode (GCE). The interaction was analyzed based on changes in the electrochemical behavior of the K₃Fe(CN)₆/K₄Fe(CN)₆ redox species under physiological pH conditions. Electrochemical parameters of the redox probe in the presence of HSA, EMPA, and the EMPA-HSA complex were measured. The alteration of the redox couple responses indicates the formation of an electro-inactive complex between the protein and EMPA. The binding parameters of the EMPA-HSA interaction, including the binding constant and complex stoichiometry, were determined, revealing the formation of EMPA-HSA complex with a binding constant of 1.03 × 10⁴M⁻¹ and a binding number of 0.624, suggesting a 1:1 stoichiometry. Molecular modeling was also conducted to further investigate the binding mode of EMPA with HSA, where the binding energy of EMPA to HSA was calculated as −4.78 kcal/mol with hydrogen bonding and hydrophobic contacts being the main interactions behind the complex formation. This research offers valuable insights into the albumin-EMPA interaction, with implications for toxicology, pharmacokinetics, and environmental impact.