Binding copper(II) ion released from azo-amino acid Schiff base complex into lysozyme crystals as models for treatment of Alzheimer’s disease

Abstract

Aim: One of the causes of Alzheimer’s disease (AD) is the structural change and aggregation of target proteins due to the binding of metal ions. In this study, we investigated where copper(II) ions bound to the protein egg white lysozyme crystals in a hydrophilic buffer solution after ions were synthesized from an amino acid Schiff base copper(II) complex with a hydrophobic azobenzene group. Methods: X-ray crystallographic studies of the complexes and egg white lysozyme were then studied. Molecular docking studies for the binding of copper(II) ion with egg white lysozyme were also carried out. Results: The results suggest that the hydrophobicity of the introduced complex affected how deeply the resultant copper(II) ion penetrated into the protein. It has been revealed that when metal complexes are soaked into protein crystals, the metal complexes act as carriers, and metal ions tend to dissociate and bind to appropriate functional groups on certain specific residues of the protein. His15 and Glu35 were the more common binding residues of the protein that bound to the metal ion. Conclusions: An anti-Irving-Williams behaviour was observed for the interaction of the copper(II) complex with the lysozyme. Docking studies revealed various potential binding sites of copper(II) ion with the lysozyme.