Figure Legends:
Figure 1. Location of di-D-amino acid substitutions. Substitutions are indicated by bolded, underlined, italicized letters. The substitutions were identical for Aβ40 and Aβ42, except for the additional ia substitution in Aβ42.
Figure 2. Oligomerization of di-D-amino acid substituted Aβ.
Peptides were cross-linked using PICUP. SDS-PAGE and silver staining were then performed to observe the effects of substitutions on (a) Aβ40 and (b) Aβ42 (see text for explanation of colored arrows and peptide designations). Mr indicates apparent molecular weight. Lanes ”M” are molecular weight markers. Positions of D-amino acid substitutions are indicated below each gel. Gels are representative of three independent experiments.
Figure 3. Fibril formation kinetics of di-D-amino acid substituted Aβ.
Peptides were prepared and mixed with Thioflavin T, which binds β-sheet and can serve as a surrogate marker for aggregation. Error bars represent standard deviations of three experiments. (A) Variants of Aβ40 with di-D-amino acid substitutions. (B) Variants of Aβ42 with di-D-amino acid substitutions.
Figure 4. Location of single D-amino acid substitutions in Aβ40 and Aβ42.
Figure 5. Oligomerization of single D-amino acid substituted Aβ.
Both non-cross-linked and cross-linked samples were analyzed. Peptide samples were prepared and cross-linked using PICUP, and then analyzed using SDS-PAGE and silver staining. (A) Non-cross-linked and cross-linked Aβ40. Several substituted peptides behaved similar to WT, (e.g., D-N27). Others only displayed monomer. (B) Oligomer distribution frequencies of select Aβ40 variants. (C) Non-cross-linked and cross-linked samples of Aβ42. (F) Oligomer distribution frequencies of Aβ42. Gels are representative of three independent experiments.
Figure 6. Fibril formation kinetics of single