Figure 4. Changes of the Trp environment induced by metal ions.

(A) Normalized 350/325 fraction in the absence (black) and presence of 1.5 equivalents of Zn(II) (red) as a function of time. (B) Normalized 350/325 fraction in the absence (black) and presence of 1.5 equivalents of Cu(II) (blue) as a function of time. This ratio was used to estimate the percentage of change in Trp environment of the protein (normalized fraction) based on protein temperature unfolding experiments, where the baseline corresponds to folded protein and the maximum value of 350/325 ratio (∼1.44) correspond to 100% unfolded proteins.