Fe2+ binding on amyloid β‐peptide promotes aggregation |
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| Authors: | Subramaniam Boopathi Ponmalai Kolandaivel |
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| Affiliation: | Department of Physics, Bharathiar University, Coimbatore, Tamilnadu, India |
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| Abstract: | The metal ions Zn2+, Cu2+, and Fe2+ play a significant role in the aggregation mechanism of Aβ peptides. However, the nature of binding between metal and peptide has remained elusive; the detailed information on this from the experimental study is very difficult. Density functional theory (dft) (M06‐2X/6‐311++G (2df,2pd) +LANL2DZ) has employed to determine the force field resulting due to metal and histidine interaction. We performed 200 ns molecular dynamics (MD) simulation on Aβ1‐42‐Zn2+, Aβ1‐42‐Cu2+, and Aβ1‐42‐Fe2+ systems in explicit water with different combination of coordinating residues including the three Histidine residues in the N‐terminal. The present investigation, the Aβ1‐42‐Zn2+ system possess three turn conformations separated by coil structure. Zn2+ binding caused the loss of the helical structure of N‐terminal residues which transformed into the S‐shaped conformation. Zn2+ has reduced the coil and increases the turn content of the peptide compared with experimental study. On the other hand, the Cu2+ binds with peptide, β sheet formation is observed at the N‐terminal residues of the peptide. Fe2+ binding is to promote the formation of Glu22‐Lys28 salt‐bridge which stabilized the turn conformation in the Phe19‐Gly25 residues, subsequently β sheets were observed at His13‐Lys18 and Gly29‐Gly37 residues. The turn conformation facilitates the β sheets are arranged in parallel by enhancing the hydrophobic contact between Gly25 and Met35, Lys16 and Met35, Leu17 and Leu34, Val18 and Leu34 residues. The Fe2+ binding reduced the helix structure and increases the β sheet content in the peptide, which suggested, Fe2+ promotes the oligomerization by enhancing the peptide‐peptide interaction. Proteins 2016; 84:1257–1274. © 2016 Wiley Periodicals, Inc. |
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| Keywords: | Alzheimer's diseases amyloid β ‐peptide metal ions molecular dynamics simulation U‐shaped conformation |
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