Effects of temperature and pH on the catalysis of PaDHPAO.

<p>(A) To evaluate the effects of temperature on activity, the <i>k’</i>_cat values were measured at 5–70°C and plotted as a function of temperature. The inset in A is the Arrhenius plot of ln(<i>k’</i>_cat) versus the reciprocal of the absolute temperature (5–55°C). The data indicate a transition temperature at 35°C (arrow). (B) To evaluate the effect of pH on activity, the apparent maximum velocities (<i>V’</i>_max) of the PaDHPAO reaction were measured under various pH conditions (4.0–10.5). A plot of the pH-rate profile indicates an optimal pH at 7.5 with two p<i>K</i>_a values of 6.5 ± 0.1 and 8.9 ± 0.1, respectively.