Aggregation of amyloid-β (Aβ) peptides correlates with the pathology of Alzheimer's disease. However, the inter-molecular interactions between Aβ protofibril remain elusive. Herein, molecular mechanics Poisson-Boltzmann surface area analysis based on all-atom molecular dynamics simulations was performed to study the inter-molecular interactions in Aβ17-42 protofibril. It is found that the nonpolar interactions are the important forces to stabilize the Aβ17-42 protofibril, while electrostatic interactions play a minor role. Through free energy decomposition, 18 residues of the Aβ17-42 are identified to provide interaction energy lower than −2.5 kcal/mol. The nonpolar interactions are mainly provided by the main chain of the peptide and the side chains of nine hydrophobic residues (Leu17, Phe19, Phe20, Leu32, Leu34, Met35, Val36, Val40, and Ile41). However, the electrostatic interactions are mainly supplied by the main chains of six hydrophobic residues (Phe19, Phe20, Val24, Met35, Val36, and Val40) and the side chains of the charged residues (Glu22, Asp23, and Lys28). In the electrostatic interactions, the overwhelming majority of hydrogen bonds involve the main chains of Aβ as well as the guanidinium group of the charged side chain of Lys28. The work has thus elucidated the molecular mechanism of the inter-molecular interactions between Aβ monomers in Aβ17-42 protofibril, and the findings are considered critical for exploring effective agents for the inhibition of Aβ aggregation.
Exploring the inter-molecular interactions in amyloid-β protofibril with molecular dynamics simulations and molecular mechanics Poisson-Boltzmann surface area free energy calculations
Fu-Feng Liu, Zhen Liu, Shu Bai, Xiao-Yan Dong, Yan Sun; Exploring the inter-molecular interactions in amyloid-β protofibril with molecular dynamics simulations and molecular mechanics Poisson-Boltzmann surface area free energy calculations. J. Chem. Phys. 14 April 2012; 136 (14): 145101. https://doi.org/10.1063/1.3702195
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