title: Molecular insight into conformational transition of amyloid β-peptide 42 inhibited by (-)-epigallocatechin-3-gallate probed by molecular simulations.
abstract: Considerable experimental evidence indicates that (-)-epigallocatechin-3-gallate (EGCG) inhibits the fibrillogenesis of Aβ(42) and alleviates its associated cytotoxicity. However, the molecular mechanism of the inhibition effect of EGCG on the conformational transition of Aβ(42) remains unclear due to the limitations of current experimental techniques. In this work, molecular dynamics simulations and molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) analysis were coupled to better understand the issue. It was found that the direct interactions between EGCG and the peptide are the origin of its inhibition effects. Specifically, EGCG molecules expel water from the surface of the Aβ(42), cluster with each other, and interact directly with the peptide. The results of free energy decomposition calculated by MM-PBSA indicate that the nonpolar term contributes more than 71% to the binding free energy of the EGCG-Aβ(42) complex, while polar interactions (i.e., hydrogen bonding) play a minor role. It was identified that there are 12 important residues of Aβ(42) that strongly interact with EGCG (Phe4, Arg5, Phe19, Phe20, Glu22, Lys28, Gly29, Leu34-Gly37, and Ile41), while nonpolar interactions are mainly provided by the side chains of some hydrophobic residues (Phe, Met and Ile) and the main chains of some nonhydrophobic residues (Lys28 and Gly29). On the contrary, polar interactions are mainly formed by the main chain of Aβ(42), of which the main chains of Gly29 and Gly37 contribute greatly. The work has thus elucidated the molecular mechanism of the inhibition effect of EGCG on the conformational transition of Aβ(42), and the findings are considered critical for exploring more effective agents for the inhibition of Aβ(42) fibrillogenesis.
authors: Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
authors: Fu-Feng
authors: FF
authors: Liu
authors: Xiao-Yan
authors: XY
authors: Dong
authors: Lizhong
authors: L
authors: He
authors: Anton P J
authors: AP
authors: Middelberg
authors: Yan
authors: Y
authors: Sun
mesh_terms: D016229:Amyloid beta-Peptides / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D056004:Molecular Dynamics Simulation; D010446:Peptide Fragments / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011485:Protein Binding; D013816:Thermodynamics
chemical_list: D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42); D002392:Catechin; C045651:epigallocatechin gallate