We present a simulation study of the early events of peptide dissociation from a fibril of the Alzheimer's Aβ42 peptide. The fibril consists of layers of two adjacent Aβ42 peptides each folded in an S-shaped structure which has been determined by solid state NMR spectroscopy of a monomorphic disease-relevant species. Multiple molecular dynamics runs (16 at 310 K and 15 at 370 K) were carried out starting from an 18-peptide protofibril for a cumulative sampling of about 15 μs. The simulations show structural stability of the fibrillar core and an overall increase in the twist to about 3 degrees. The N-terminal segment 1-14 is disordered in all peptides. At both ends of the fibril, the central segment 21-29, which includes part of the β2 strand, dissociates in some of the simulations. The β1 and β3 strands, residues 15-20 and 35-41, respectively, are structurally stable. The transient binding of the N-terminal stretch to the β3 strand of the adjacent peptide at the tip is likely to contribute to the arrest phase of the stop-and-go mechanism.
BT - The Journal of Physical Chemistry B C1 - 0237 DA - 2018 Jul 17 DO - 10.1021/acs.jpcb.8b05236 IS - 49 J2 - J. Phys. Chem. B LA - eng M3 - Research Article N2 -We present a simulation study of the early events of peptide dissociation from a fibril of the Alzheimer's Aβ42 peptide. The fibril consists of layers of two adjacent Aβ42 peptides each folded in an S-shaped structure which has been determined by solid state NMR spectroscopy of a monomorphic disease-relevant species. Multiple molecular dynamics runs (16 at 310 K and 15 at 370 K) were carried out starting from an 18-peptide protofibril for a cumulative sampling of about 15 μs. The simulations show structural stability of the fibrillar core and an overall increase in the twist to about 3 degrees. The N-terminal segment 1-14 is disordered in all peptides. At both ends of the fibril, the central segment 21-29, which includes part of the β2 strand, dissociates in some of the simulations. The β1 and β3 strands, residues 15-20 and 35-41, respectively, are structurally stable. The transient binding of the N-terminal stretch to the β3 strand of the adjacent peptide at the tip is likely to contribute to the arrest phase of the stop-and-go mechanism.
PY - 2018 EP - 11072–11082 T2 - The Journal of Physical Chemistry B TI - Disorder at the tips of a disease-relevant Aβ42 amyloid fibril: A molecular dynamics study VL - 122 SN - 1520-5207 ER -