Figure 1.
GSPE attenuates aggregation of Aβ peptides into soluble oligomeric forms in vitro. A, B, Dose-dependent inhibition by GSPE of synthetic Aβ1–42 or Aβ1–40 peptide aggregation into HMW oligomeric Aβ forms. Aβ1–42 (final concentration 50 μg/ml) or Aβ1–40 (final concentration 50 μg/ml) peptide was incubated with various concentrations of GSPE [lanes 1–6, 0, 0.2, 1, 5, 25, and 100 μm; CTR (control) are samples without incubation] at 37°C for 24 h. Bands were visualized by Western blot analysis probed with 6E10 antibody. C, D, SDS-PAGE of Aβ1–42 and Aβ1–40 in the presence or absence of GSPE after PICUP (see Materials and Methods). Aβ1–42 or Aβ1–40 was cross-linked in the presence or absence of 50 μm GSPE, and the bands were visualized using silver staining. CTR, Non-cross-linked Aβ1–42 (C) or Aβ1–40 (D); lanes 1 and 2, Aβ peptide with 1× Ru(Bpy) and APS in the absence and presence of GSPE; lanes 3 and 4, Aβ peptide with 2× Ru(Bpy) and APS in the absence and presence of GSPE. The data are representative of results obtained in each of three independent experiments. The ∼13.5 kDa (trimer) bands are an SDS-induced artifact (Bitan et al., 2003).