Exchange dynamics of Zn(II)- and Ag(I)-Aβ complexes
characterized
by NMR relaxation dispersion experiments. (a, b) Distinct residues
exhibit significantly high amplitude 15N CPMG relaxation
dispersion profiles for Zn(II)-Aβ40 (blue) and Ag(I)-Aβ40
(green) complexes, where the absolute chemical shift changes are plotted,
obtained from a global fit analysis. The temperature dependence of
the relaxation dispersion profile for two selected residues, E3 and
V12, is displayed, where circles correspond to 278 (red), 281 (yellow),
284 (green), 287 (blue), and 290 K (violet) in the presence of metal
ions. Black squares reflect the dynamics without any metal ions added.
(c, d) The population of the NMR invisible state and the exchange
rate between the two states exhibit very similar temperature dependences
for Zn(II) and Ag(I). (e) The binding model is visualized where in
the NMR invisible state the N-terminus encapsulates the metal ion,
forming a more compact “folded” complex. Data were replotted
from refs (2) and (3).