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Molecular dynamics studies of hexamers of amyloid‐β peptide (16–35) and its mutants: Influence of charge states on amyloid formation
Author(s) -
Han Wei,
Wu YunDong
Publication year - 2006
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.21232
Subject(s) - chemistry , mutant , amyloid (mycology) , peptide , hydrogen bond , molecular dynamics , solvation , biophysics , side chain , wild type , biochemistry , molecule , computational chemistry , solvent , organic chemistry , inorganic chemistry , biology , gene , polymer
To study the early stage of amyloid‐β peptide (Aβ) aggregation, hexamers of the wild‐type (WT) Aβ 16–35 and its mutants with amyloid‐like conformations have been studied by molecular dynamics simulations in explicit water for a total time of 1.7 μs. We found that the amyloid‐like structures in the WT oligomers are destabilized by the solvation of ionic D23/K28 residues, which are buried in the fibrils. This means that the desolvation of D23/K28 residues may contribute to the kinetic barrier of aggregation in the early stage. In the E22Q/D23N, D23N/K28Q, and E22Q/D23N/K28Q mutants, hydration becomes much less significant because the mutated residues have neutral amide side‐chains. These amide side‐chains can form linear cross‐strand hydrogen bond chains, or “polar zippers”, if dehydrated. These “polar zippers” increase the stability of the amyloid‐like conformation, reducing the barrier for the early‐stage oligomerization. This is in accord with experimental observations that both the D23/K28 lactamization and the E22Q/D23N mutation promote aggregation. We also found that the E22Q/D23N mutant prefers an amyloid‐like conformation that differs from the one found for WT Aβ. This suggests that different amyloid structures may be formed under different conditions. Proteins 2007. © 2006 Wiley‐Liss, Inc.