Figure 1.

Thermally induced changes in the Trp fluorescence of EI(H189A) in Buffer A with 2 mM ME and added effectors at 30°C/h scan rate. Added effectors in the presence of 2 mM Mg²⁺ are 5 mM pyruvate (open diamonds), 5 mM pyruvate and 0.2 mM PEP (open triangles), 5 mM pyruvate and 1 mM PEP (open circles), or 1 mM PEP (open squares). Transition temperatures are indicated by arrows, and the solid line for each data set shows the fit to a two-state unfolding model.