ELISA.

<p>Optical density (OD) at 450 nm measured at 2.5 h of pNPP incubation. OD for the different compounds at different concentrations is given. A and B illustrate the ability of the compounds to recognize Aβ fibrils. They indicate two series of experiments performed with following compounds A: ACI-80-Kφ to ACI-86-Kφ. ACI-80 without φ-label was run as a control. B: ACI-87-Kφ to ACI-89-Kφ, as well as fluorinated derivatives. ACI-80-Kφ, ACI-82-Kφ and ACI-83-Kφ were included as controls. C and D illustrate the ability of the compounds to recognize peptide film which largely consists of Aβ monomers.</p

Surface plasmon resonance analysis of the interaction between immobilized Aβ1–42 fibrils and ACI-80-Kφ and various derivatives (Kφ presents a lysine (K) covalently linked to a fluorescein isothiocyanate (φ).

<p>ACI-80 derivatives were solved in running buffer (PBS, pH 7.4). The injected volume of ACI-80 derivatives was 10 µl of a 50 µg/ml concentration using a flow rate of 5 µl/min. The response of ACI-80-Kφ in resonance units [RU] was defined as 100%. Values >100% denote increased Aβ interaction of the ACI-80 derivative in comparison to ACI-80-Kφ. All derivatives were φ-labeled. Only the variations in comparison to ACI-80-Kφ are indicated in the figure.</p

Pyroglutamate content of ACI-80, ACI-80-Kφ and [¹²⁷I]-ACI-80.

<p>Kφ presents a lysine (K) linked to a fluorescein isothiocyanate (φ).</p

D-enantiomeric peptide variants binding to fibrillar Aß1–42, covalently immobilized on a CM5 sensor chip via amine coupling.

<p>For each peptide variant experimental sensorgrams (black traces) obtained with injections at 2500 nM, 12500 nM and 62500 nM (ACI-80-Kφ, ACI-87-Kφ) or 500 nM, 2500 nM and 12500 nM (ACI-88-Kφ, ACI-89-Kφ) are shown. Injections were performed for 60 seconds each and dissociation phases were recorded for at least 30 seconds. The sensorgrams were globally fit (red curves) to a heterogeneous ligand model accounting for different refractive indices.</p

ELISA: Mean binding values for compounds with concentration of 10 µg/ml.

<p>All values were compared to that of ACI-80-Kφ. Compound binding to compound film, containing predominantly monomers and to fibrils was measured. Average values of two or three experiments unless marked otherwise. *value of one single experiment only. Kφ presents a lysine (K) linked to a fluorescein isothiocyanate (φ).</p

Results of the binding assays for ACI-80-Kφ derivatives to Aβ1–42 fibrils using surface plasmon resonance.

<p>Interaction and dissociation was measured with respect to the maximal interaction signal during injection and the response 60 s after the end of injection, respectively. ACI-80-Kφ binding was defined as 100%. Kφ presents a lysine (K) linked to a fluorescein isothiocyanate (φ).</p

<i>Ex vivo</i> staining of brain tissue sections from 13 months old male double transgenic AD mice APP (V717I) x PS1 (A246E) using different φ-labeled ACI-80 derivatives, 6E10-Aβ-antibody and DAPI.

<p>Left column: triple image overlay of respective stains reveal that the φ-compounds identify plaques. White scale bars 20 µm. Results of non-transgenic litter mate controls are not shown as no staining of φ-labeled ACI-80 derivatives and 6E10-Aβ-antibody could be detected.</p

List of investigated D-enantiomeric peptide compounds.

<p>Modifications in the original amino acid sequence of ACI-80 are printed in bold. Amino acid residues are given in the one-letter-code. All amino-acids are D-enantiomers. Kφ presents a lysine (K) linked to a fluorescein isothiocyanate (φ).</p

Results for compound – Aβ fibril interactions obtained with the heterogeneous ligand model.

<p>Results for compound – Aβ fibril interactions obtained with the heterogeneous ligand model.</p

Photomicroscope images of mouse brain sections (female APP (V717I) × PS1 (A246E), age 24.3 months) in light microscope.

<p>Overview (left panel) and higher magnification (right panel). The brain slices were incubated with ACI-89-Kφ-peptide binding to plaques was visualized using an anti-fluorecein isothiocyanate 1 antibody and alkaline phosphatase as chromogenic detection. This revealed the high sensitivity of this method and the presence of abundant plaques in the tg mouse brain.</p