Effect of Cu²⁺ on the binding of catechins to zein through multi-spectral and in silico analyses

This study aimed to elucidate how Cu²⁺ influences the interaction between catechins and zein using multi-spectral and molecular modeling techniques. As a result, UV-vis spectra revealed characteristic changes, indicating chelation between catechins and Cu²⁺ at a 1:1 M ratio. Fluorescence spectra further confirmed interaction through a static quenching mechanism between catechins/catechin-Cu²⁺ complexes and zein. Catechins induced changes in the microenvironment and hydrophobicity surrounding the binding site of zein, whereas Cu²⁺ had minimal impact on these aspects. CD spectra underscored catechins' role in altering zein's secondary structure conformation, alongside Cu²⁺. Various types of interactions (hydrophobic, hydrogen bonding, electrostatic, and van der Waals) contributed to the binding of catechins/catechin-Cu²⁺ complexes with zein. Molecular modeling elucidated key residues and binding conformations, highlighting the significance of hydrophobic interactions and hydrogen bonding in their association. These findings not only deepen our understanding of catechin-Cu²⁺-zein interactions but also underscore their potential applications in the food industry.