Phosphorescence Activation Energies

As mentioned before the phosphorescence decay of WT in D₂O buffer is biphasic. An Arrhenius plot of these two lifetimes indicate that the non-radiative decay processes they represent have different activation energies [Figure 3a, below]. In addition, these activation energies are very similar to those observed for fully deuterated or protonated WT at equilbrium [Figure 3b, below]. This supports our idea that the longer lifetime observed during exchange corresponds to a deuterated state and the shorter lifetime to a protonated state.

Figure 3a: Arrhenius plot of the equilbirum phosphorescence lifetimes of fully protonated and fully deuterated WT-AP.

Figure 3b: Arrhenius plot of the long short lifetime components observed with WT-AP is mixed into D₂O buffer.

Determining Exchange Kinetics