Figure 9. Variation of the change in the unfolding enthalpy (Delta H, in kcal/mol) with the midpoint transition temperature (Tm, in [degree sign]C). Each point represents a separate experiment: filled circles for the isoflurane series and open circles for the halothane series. As expected, Delta H increased with increasing Tm. Best fit lines were Delta H = 157 + 5.6(Tm- 61.3) for isoflurane and Delta H = 158 + 5.7(Tm- 61.9) for halothane. These best fit lines for Delta H were used to calculate the normalized equilibrium constants (shown in Figure 10) from the change in T (m) attributable to added anesthetic agents.