Figure 1.
One-dimensional NMR proton spectra of Aβ peptides.
Aromatic/amide regions of A) Aβ42WT and B) Aβ42Nle35p37 in 10% DMSO/PBS, pH 7.2, at 25°C.
Figure 2.
CD spectroscopy of the Aβ42Nle35p37 and Aβ42WT peptides.
Aβ42WT takes beta-sheet rich fibrils (curve WT) while Aβ42Nle35p37 shows a large negative peak around 197 nm indicating disordered structure (curve Mut). Thioflavin T fluorescence of Aβ42WT and Aβ42Nle35p37 peptides are shown in the inset. Data was measured at 25°C.
Figure 3.
AFM images of Aβ peptide preparations.
A) Representative 1.0×1.0-µm x-y, 10-nm total z-range AFM micrograph of Aβ42WT preparation. Observed are irregularly shaped and sized aggregate particles, some connected by fibrils. B) A surface plot of the boxed region of (A) clearly showing the aggregate with connected fibril. C) Representative 1.0×1.0-µm x-y, 10-nm total z-range AFM micrograph of Aβ42Nle35p37 preparation showing discrete globular aggregates of uniform size and density.
Figure 4.
Two-dimensional NMR proton spectra of Aβ peptides.
2D 1H-1H spectra of Aβ42Nle35p37 (A, B, C) and Aβ21–43Nle35p37 (D, E, F). TOCSY of (NH-Hα) region of the Aβ42Nle35p37 (A) and Aβ21–43Nle35p37 (D). NOESY of (NH-Hα) region of Aβ42Nle35p37 (B) and Aβ21–43Nle35p37 (E). NOESY of (NH-NH) region of Aβ42Nle35p37 (C) and Aβ21–43Nle35p37 (F). Data was measured at 15°C in 10% DMSO-d6, PBS, pH 7.2.
Table 1.
Chemical shift assignments of Aβ42Nle35p37.
Table 2.
Chemical shift assignments of Aß21–43Nle35p37.
Figure 5.
5 structures were taken at 1 ns intervals from the computational structure refinements. Shown are the six residues around the turns (solid color rendering for the four residues around the turns, semi-transparent for the leading and trailing residues), backbone heavy-atoms shown for all residues, and side-chain heavy-atoms included for the four residues around the turns. (A) The V24-N27 turn is observed in most SS-NMR studies, and as show here has a conformation similar to previous unconstrained MD simulations. (B) The induced beta-turn from the d-Pro mutation, V36-V39, is clearly defined.
Figure 6.
One- and two-dimensional NMR spectra of Aβ peptide mixtures.
1D proton spectra of the aromatic/amide regions of 1∶4 (A) and 4∶1 (B) mixtures of Aβ42Nle35p37∶Aβ42WT. (C) 2D 1H-15N HSQC (Heteronuclear Single Quantum Coherence) experiment of the 4∶1 Aβ42Nle35p37∶Aβ42WT mixture (Aβ42WT uniformly 15N-labeled), in 10% DMSO/PBS, pH 7.2, at 25°C. (D) 2D 1H-1H TOCSY (NH-Hα) region of the 4∶1 Aβ42Nle35p37∶Aβ42WT mixture, in 10% DMSO/PBS, pH 7.2.