Fig. 4.

Atomic expansion dynamics of a single amyloid-like microcrystal measured using 4D electron microscopy. (A) The single 3D microcrystal displays an expansion of the β-sheets of 11 $\pm$ 4.0$\times {10}^{-4}$, whereas the dynamics along the [0 0 4] direction shows that there is a much larger expansion of 28 $\pm$ 8.0$\times {10}^{-4}$ in the interprotofilament direction. (B, Left) Schematic of the expansion of the protofilament–protofilament interface with the stabilizing bifurcated hydrogen bonds (dashed black lines) highlighted by two gray boxes. Individual β-strands are shown as cyan ribbons. (B, Right) A cross-section of the electrostatic potential surface of the protofilament–protofilament complex is shown ranging from +3 kcal⋅mol⁻¹ per electron (blue) to −3 kcal⋅mol⁻¹ per electron (red), with white representing uncharged regions of the constituent peptides. For clarity, an overlaid ribbon and stick representation makes individual sidechains more identifiable. The cross-β structure was created using PDB ID code 3OVL.