Fig. 3.

Changes in the structure and dynamics of CRES upon amyloidogenesis. (A, Left) Overlay of a region from the 2D ¹⁵N,¹H HSQC spectra of 1.4 mM CRES at pH 6/250 mM NaCl (black contours), pH 7.5/173 mM NaCl (blue contours), and pH 7.5/0 mM NaCl (red contours). (A, Right) Calculated CSPs mapped onto the crystal structure of CRES. The CSPs between pH 6/250 mM NaCl and pH 7.5/173 mM NaCl are given as a gray-to-blue gradient, and the CSPs between pH 6/250 mM NaCl and pH 7.5/0 mM NaCl are given as a gray-to-red gradient. (B) Plot of the ΔR₂ versus residue number. Blue points are the differences between pH 6/250 mM NaCl and pH 7.5/173 mM NaCl, and the red points are the differences between pH 6/250 mM NaCl and pH 7.5/0 mM NaCl. The error in the values, propagated from the covariance matrix of the fits, are shown as gray bars. The blue and red dashed lines highlight the average difference in ΔR₂ for the two conditions. (C) Representative relaxation dispersion CPMG profiles are shown for CRES at pH 6/250 mM NaCl (black circles), pH 7.5/173 mM NaCl (blue triangles), and pH 7.5/0 mM NaCl (red squares) collected at 600 MHz and 25 °C. Error bars are derived from duplicate measurements of R_2,eff at two CPMG fields. Solid lines are fit to the Bloch-McConnell equations describing two-site exchange. Below the plots, the residues for which chemical exchange phenomenon are observed are shown as sticks on the crystal structure.