Fig. 4

A putative model of the heritable Iowa mutation in interface B. a Fiber diffraction patterns of Aβ 1–42, Aβ^20–34, Aβ^{20–34, isoAsp23}, and Aβ^{20–34, Asp23Asn}. All fibers including Aβ 1–42 were prepared in 50 mM Tris, pH 7.6, 150 mM NaCl, and 1% dimethyl sulfoxide (DMSO), except Aβ^{20–34, Asp23Asn}, in which the DMSO concentration was raised to 5%. b Intensities of reflections from fiber diffraction of the segments were plotted against D spacing. Radial intensity values are vertically  staggered for visibility of peaks. c From left to right, interface B down the fibril axis of Aβ^20–34 structure, a model Aβ^{20–34, Asp23Asn} on the backbone of the Aβ^20–34 structure, Aβ^{20–34, isoAsp23} structure, and a model Aβ^{20–34, Asp23Asn} on the backbone of the Aβ^{20–34, isoAsp23} structure. d A view perpendicular to the fibril axis of residues 23–24 of each structure. Yellow dashed lines represent measured distances in Å between the amide carboxyl of residue 23 and the amide nitrogen of Val24 on the adjacent strand. Source data are provided as a Source Data file