Zn(2+) effect on structure and residual hydrophobicity of amyloid β-peptide monomers.

The aggregation of amyloid β-peptide (Aβ peptide) has been associated with the pathogenesis of Alzheimer's disease (AD). In the present study, we aimed to disclose how Zn(2+) affects the Aβ aggregation in detail. Thus, molecular dynamics simulation was implemented to elucidate the changes of structure and residual hydrophobicity upon Zn(2+) coordination. Our results show that Zn(2+) can strongly influence the structural properties of Aβ40 and Aβ42 by reducing helical formation and increasing turn formation to expose the hydrophobic regions. Furthermore, hydrophobicity of Zn(2+)-Aβ40 and Zn(2+)-Aβ42 was much higher than that of each monomer, since Zn(2+) binding can significantly influence the hydrophilic domains of Aβ. The further analyses indicate that not only four residues (H6, E11, H13, and H14) but also R5, D7, K16, K28, and terminal residues influence hydrophobicity upon Zn(2+) coordination. Importantly, R5, K16, and K28 play a crucial role to regulate solvation-free energies. This work is helpful to understand the fundamental role of Zn(2+) in aggregation, which could be useful for further development of new drugs to inhibit Zn(2+)-Aβ aggregation.