Quantum-Chemical Evaluation of the Interaction Between Copper(II) Ions and Silk Fibroin Macromolecules
Keywords:
silk fibroin, copper complex, quantum chemistry, molecular docking, PM3 method, CHARMM22, coordination bond, binding energy.Abstract
In this study, the interaction between copper(II) ions and silk fibroin macromolecules was investigated using quantum-chemical and molecular modeling methods. The main goal was to evaluate the structural and energetic stability of Cu(II)–fibroin complexes and to determine the amino acid residues responsible for metal coordination. Molecular docking and semi-empirical PM3 calculations with the CHARMM22 force field were employed to optimize the Cu–fibroin structures. The results demonstrated that Cu(II) ions preferentially bind to the –COO⁻, –OH, and –NH₂ groups of Asp, Ser, and His residues, forming energetically favorable complexes with ΔG values ranging from –4.0 to –4.6 kcal/mol. Theoretical IR spectra were found to be consistent with experimental ATR–FTIR data. The study provides insight into the coordination behavior of silk fibroin and establishes a theoretical basis for the design of silk-based metal complexes with potential biomedical and environmental applications.
