Fig. 2. (A) Temperature dependence of _max (open circles) was used to calculate the Arrhenius activation energies (E_a) for lactate dehydrogenase (LDH) in crude tissue homogenates from the slope of Arrhenius plots [10³/T K against ln(_max)]. (B) The enthalpy–entropy compensation plot was compiled from different sources for purified LDH (Hochachka and Somero, 1984; Low et al., 1973; Place and Powers, 1984; Prosser, 1986; Somero and Low, 1976; Uvarov and Archakov, 1990) and used to calculate thermodynamic parameters (H, S, G). Results of linear regression are given ± S.E.M.