FIGURE 3.

(a) Normalized enthalpy distributions of the three CS° of SW MbCO in the presence of 10 atm of xenon (solid lines) and in the absence of xenon (dotted lines). (b) Arrhenius plots of k_peak of CO geminate rebinding with the taxonomic substates A₀, A₁, and A₃ of SW Mb in the presence of 10 atm of xenon (solid lines) and in the absence of xenon (dotted lines). The solvent was 79% glycerol water (w/w). The rate distributions changes induced by xenon are not fully saturated at a pressure of 10 atm. In fact, we estimated to ∼3 atm the value for half saturation (from a titration of the difference performed at the log k_peak value). However, one experiment performed at 16 atm yielded data that were so close to the former that one may regard the thermodynamic parameters determined at 10 atm as a good approximation of their true values.