Characterization of caffeic acid-induced changes in the structure and stability of lysozyme: insights from spectroscopy and molecular dynamics simulations

This study aimed to examine the influence of Caffeic Acid on the structural, functional, and thermal stability characteristics of lysozyme (LYZ), a critical enzyme that plays a vital role in the immune system. Initially, the Caffeic Acid-LYZ binding interaction was scrutinized through a combination of spectroscopic techniques: UV-Vis's absorption spectra, circular dichroism (CD), and fluorescence spectroscopy. The UV-Vis absorption spectra analysis indicated an augmentation in the absorption of LYZ at 280 nm upon exposure to Caffeic Acid. Additionally, the findings from fluorescence spectroscopy pointed toward the formation of a ground-state complex, as deduced from the static quenching of LYZ fluorescence. Based on the thermodynamic analysis, it was found that the binding process exhibited spontaneity, and the predominant stabilizing forces for the complex were found to be hydrogen bonds and van der Waals forces. The kinetic experiment also demonstrated that the LYZ's activity was reduced consequently to the addition of Caffeic Acid. Further, the CD values showed the conformational changes in the enzyme during complexation. The complementary computational approaches corroborated the empirical results derived from spectroscopic investigations. Molecular docking predicted the most favorable binding site for Caffeic Acid on LYZ, while molecular dynamics simulations confirmed the stability of the resulting complex.