Volume 3, Issue 5, Pages 898-912 (November 2017) Photochemical Identification of Molecular Binding Sites on the Surface of Amyloid-β Fibrillar Aggregates Amir Aliyan, Thomas J. Paul, Bo Jiang, Christopher Pennington, Gaurav Sharma, Rajeev Prabhakar, Angel A. Martí Chem Volume 3, Issue 5, Pages 898-912 (November 2017) DOI: 10.1016/j.chempr.2017.09.011 Copyright © 2017 Elsevier Inc. Terms and Conditions
Chem 2017 3, 898-912DOI: (10.1016/j.chempr.2017.09.011) Copyright © 2017 Elsevier Inc. Terms and Conditions
Figure 1 Binding Assay and Job Plot for the Binding of [Re(CO)3(dppz)(Py)]+ to Aβ Fibrils (A) Photoluminescence of [Re(CO)3(dppz)(Py)]+ at different concentrations ranging from 1 to 60 μM in the presence of 4 μM fibrillar Aβ (red dots) and in buffer (black triangles). The black line is the fit that corresponds to a dissociation constant of 2.8 ± 0.6 μM. (B) Job plot performed at a constant total concentration ([Re(CO)3(dppz)(Py)]+ + [Aβ fibrils]) of 50 μM. The maximum lies around a [Re(CO)3(dppz)(Py)]+ mole fraction of 0.26. Each point and error bar corresponds to the average and standard deviation, respectively, of at least three independent measurements. Chem 2017 3, 898-912DOI: (10.1016/j.chempr.2017.09.011) Copyright © 2017 Elsevier Inc. Terms and Conditions
Figure 2 Docking Results of the Aβ Fibril Docking results from rigid docking on different conformations of the two-fold Aβ1–40 fibril, where the flexibility of the ligand was maintained and conformation space of the fibrils sampled. Sites with the highest interactions: (A) sites A+A’ and B+B’, (B) interaction percentages of all binding sites, (C) sites C+C’ and D+D’, and (D) sites E and F. Chem 2017 3, 898-912DOI: (10.1016/j.chempr.2017.09.011) Copyright © 2017 Elsevier Inc. Terms and Conditions
Figure 3 MS-MS Analysis of Aβ Pristine and oxidized Aβ separated by LC-MS were subjected to MS-MS analysis. The masses for (A) the y ions with (B) the MS-MS spectrum and (C) the b ions with (D) the MS-MS spectrum around methionine are presented. Pristine (blue) and oxidized (red). Chem 2017 3, 898-912DOI: (10.1016/j.chempr.2017.09.011) Copyright © 2017 Elsevier Inc. Terms and Conditions
Figure 4 Binding Modes for [Re(CO)3(dppz)(Py)]+ to Site A on the Two-Fold Structure of the Aβ Fibril The primary mode (A) and the secondary mode (B) of [Re(CO)3(dppz)(Py)]+ binding to CH-Π and Π-Π interactions are visible (dotted lines). Distances and interacting residues are labeled. Chem 2017 3, 898-912DOI: (10.1016/j.chempr.2017.09.011) Copyright © 2017 Elsevier Inc. Terms and Conditions
Figure 5 MD Simulations of Molecular Oxygen Showing Oxygen Pockets Near Met35 Residues (A) Two-fold Aβ structure showing the hydrophobic zipper with oxygen binding positions. (B–D) Site 1 (B) shows interactions of two oxygen molecules (O1 and O2), site 2 (C) shows the interactions of the O3 oxygen molecule, and site 3 (D) shows the interactions between the O4 oxygen molecule and Aβ residues. Chem 2017 3, 898-912DOI: (10.1016/j.chempr.2017.09.011) Copyright © 2017 Elsevier Inc. Terms and Conditions
Figure 6 Scheme of Aβ1–40 Cross-section The binding site for [Re(CO)3(dppz)(Py)]+ (blue circles) and the location of methionine 35 photooxidation (red circles). Oxidizable amino acids are marked in red in the Aβ sequence. Chem 2017 3, 898-912DOI: (10.1016/j.chempr.2017.09.011) Copyright © 2017 Elsevier Inc. Terms and Conditions