As mentioned, in Aβ-Zn(II) complexes, coordination is almost exclusively given through glutamic/aspartic acid and histidine amino acids, which are charged and neutral amino acids. While charged amino acids primarily interact through electrostatic interactions, neutral amino acids mostly interact through covalent interactions. Although hard metals like copper and iron favour electrostatic interactions over covalent interactions and soft metals favor covalent interactions, Zn(II), an in-between metal, can present both interactions.