Figure 3.

Solution NMR analysis of fibril formation of Aβ40-WT, Aβ42-WT, Aβ40-Dutch, and Aβ40-Iowa. Influence of temperature cycling on the ¹H–¹⁵N HSQC resonances of the four Aβ peptides. The temperature was cycled between 4 °C and either (A) 25 or (B) 37 °C. The intensity of the ¹H–¹⁵N HSQC NMR resonances was measured at 4 °C immediately after preparation and filtering of the Aβ samples at this temperature. Peak volumes were extracted at each time point and normalized to the time zero peak intensities. Normalized values were averaged across all four ¹⁵N labels; error bars represent the standard deviation. Aggregation of monomeric Aβ into oligomers, protofibrils, and fibrils as the samples are incubated at higher temperature results in the loss of NMR intensity. Incubation for the HSQC experiments was performed under quiescent conditions. (C–J) TEM images of fibril formation of Aβ40-WT, Aβ42-WT, Aβ40-Dutch, and Aβ40-Iowa. TEM micrographs of Aβ40-WT, Aβ42-WT, Aβ40-Dutch, and Aβ40-Iowa are shown after incubation for 24 h at (C–F) 25 and (G–J) 37 °C. The TEM samples were prepared from the samples used in the NMR analysis. Scale bars are 50 nm.