Figure 5.

A van’t Hoff plot of the dependencies of allosteric coupling constants on temperature. Temperature dependence was determined in an “open system” experimental design in which pH was held constant at pH 9.0. Data were collected both in Tris (solid circles and thin solid fit line) and TAPS (open squares and dashed line) buffers. Lines represent the best fits to Eq. 7. Error bars are error estimates made during the fitting of K_app-PEP to Eq. 5. Because of the “open system” design, which maintains constant pH at all temperatures, buffer ionization should not influence the data trend, and therefore, data collected in both Tris and TAPS buffers can be treated equally. The thick solid line in each panel represents data fits for the combined Tris and TAPS data, and parameters obtained from the fitting of this combined data are included in Table S2.