Metal ions such as those of copper and zinc are considered to accelerate initial formation of amyloid fibril of amyloid-β (Aβ) peptides. In this study, the role of a zinc ion for Aβ peptide aggregation was investigated by the classical molecular dynamics (MD) simulations. The MD results indicated that the negatively-charged residues gained large stabilization in the existence of a zinc ion. On the other hand, histidine and tyrosine which were reported as making a bond with a metal ion were slightly stabled. Therefore, a zinc ion is thought of as combining with histidine or tyrosine after being attracted by negatively-charged residues, because these residues exist near negatively-charged residues. These results indicate that the metal-containing system needs to be treated by quantum-mechanical techniques.
Solvation change induced by a chemical reaction can move a macromolecule in a specific direction. The hydrodynamic effect on a solvation motor was studied by using molecular dynamics simulations with a simple model. We examined the dependence of motor displacement induced by the chemical reaction on the size of the basic cell. The size dependence given by the simulation sat on a straight line as a function of the system size, and the displacement in an infinite system was estimated from the plot.