Exploration of the micellization behavior of sodium dodecyl sulfate in aqueous solution of gastric enzyme pepsin: Assessment of the consequences of sodium electrolytes and temperature.

This study explores the interactions between pepsin and sodium dodecyl sulfate (SDS) using conductometric analysis and molecular docking to deepen our understanding of the role of pepsin. Conductometric studies were conducted to examine the micellization behavior of SDS with pepsin in aqueous solutions of various sodium electrolytes (NaBr, Na₂SO₄, Na₃PO₄, and CH₃COONa) at temperatures ranging from 300.55 K to 320.55 K in 5 K increments. The critical micelle concentration (CMC) of the SDS-pepsin system was influenced by pepsin concentration, electrolyte type, and temperature. Pepsin was found to inhibit SDS micellization, increasing the CMC, while electrolytes promoted micellization, decreasing the CMC. Thermodynamic parameters-Gibbs free energy (∆G), enthalpy (∆H), and entropy (∆S)-were analyzed to identify the driving forces behind micellization. The negative ∆G indicated spontaneous aggregation, with ∆H and ∆S suggesting hydrophobic and electrostatic interactions. Molecular docking further confirmed these interactions, revealing binding between the hydrophobic tail of SDS and nonpolar binding pocket of pepsin at the interdomain cleft. These findings provide insights into surfactant-enzyme interactions, with potential applications in biochemistry, pharmacology, and food science.