Figure 4.

Good agreement between experimental and simulated R₁ and R₂ relaxation rates for the C12 region of HTTex1. (A) Shown is a comparison between R₁ and R₂ rates that were measured from fibrils of HTTex1 with a C-terminal His-tag and the equivalent relaxation rates calculated from simulations of the same construct. Proline residues are omitted because of the absence of an amide proton. Error bars indicate standard errors of the fits. (B) Shown is the same comparison as in (A) but between data and simulations of HTTex1 fibrils without a C-terminal His-tag. Experiment and simulations agree better for the HTTex1 fibrils without a His-tag, presumably because of the charge repulsion of the His-tag in our experiments that was not captured by our simulations. In the absence of a His-tag, most R₁ rates are within the margin of error of their calculated counterparts. The experimental R₂-values are slightly higher than those calculated from simulations because of residual coherent dephasing that leads to higher apparent R₂ rates. Experimental relaxation rates have been previously reported in (15). To see this figure in color, go online.