Tyrosine fluorescence spectra for the determination of Cu²⁺ binding affinity.

<p>(A) Aβ1-16, (B)Aβ1-24, (C)Aβ1-29, (D)Aβ1-35, (E)Aβ1-40. The concentration of Aβ peptides was 10 µM. The solid lines represent the best fitting curve using the independent two-Cu mode, whereas dot lines show the fitting curve simulated using one-Cu mode as depicted in the section of material and methods.</p

The content of secondary structure for the different Aβ peptides in the presence or absence of Cu²⁺ as calculated from CD spectra.

<p>*NRMSD (normalized root mean square standard deviation)  =  [(θ_obs(λ)-θ_cal(λ))²/(θ_obs(λ))²]^1/2.</p

The aggregation profiles.

<p>The aggregation profile determined by turbidity assay in the absence (A) and the presence (B) of Cu²⁺ for different Aβ peptides, (⋄) Aβ1-16, (▾) Aβ1-24, (▴) Aβ1-29, (○) Aβ1-35, and (▪) Aβ1-40.</p

The TEM images of Aβ fibril morphologies.

<p>Images A, C, E and G represent the fibril morphologies for Aβ1-40, Aβ1-35, Aβ1-29 and Aβ1-16 with Cu²⁺ stripped off by EDTA, respectively. Images B, D, F and H represent the morphologies for Aβ1-40, Aβ1-35, Aβ1-29 and Aβ1-16 in the presence of Cu²⁺, respectively.</p

The plot of secondary structure content vs. Cu²⁺ concentration.

<p>The plot for different Aβ peptides, (▪) Aβ1-16, (♦) Aβ1-24, (▴) Aβ1-29, (○) Aβ1-35, (▾) Aβ1-40 and (A) β–sheet percentage, (B) random coil percentage, and (C) α-helx. (D) The plot of β–sheet propensity vs. Aβ peptides.</p

Circular dichroism spectra of Aβ peptides.

<p>CD spectra for different Aβ peptides, (▿) Aβ1-16, (□) Aβ1-24, (•) Aβ1-29, (○) Aβ1-35, (▪) Aβ1-40, in the absence (A) and presence (B) of Cu²⁺. The concentration for both Aβ peptides and Cu²⁺ used in measurements was 30 µM. A normalized root mean square standard deviation (NRMSD) parameter was introduced to indicate for the quality between observed and calculated CD spectra.</p

The plot of DCF fluorescence intensity vs. Aβ concentration.

<p>The plot for different Aβ peptides, (▴) 30 µM Cu²⁺ alone, (♦) Aβ1-16, (▵) Aβ1-24, (•) Aβ1-29, (○) Aβ1-35, (◊) Aβ1-40, and (▿) Aβ25-35 in the presence of 30 µM Cu²⁺. Instead of generating H₂O₂, most Aβ peptides, except of Aβ25-35, inhibit the generation of H₂O₂. All measurements were measured after the fresh prepared samples were incubated at 37°C for 1 hr.</p

The estimated EPR parameters of Aβ/copper (II) complex for the different Aβ peptides.

<p>The estimated EPR parameters of Aβ/copper (II) complex for the different Aβ peptides.</p

The estimated copper (II) binding constant using one-Cu and dependent two-Cu models for the different Aβ peptides.

<p>The estimated copper (II) binding constant using one-Cu and dependent two-Cu models for the different Aβ peptides.</p