Temperature dependence of chemiluminescence in aqueous solutions of aspartate in the presence of hydrogen peroxide and ethidium bromide

The effect of cyclic variations of temperature in the ranges 25-46 degrees C and 35-37 degrees C on the intensity of chemiluminescence in aqueous solutions of L-Asp and L-Glu in the presence of H2O2 and ethidium bromide was studied. It is shown that the Arrhenius plots are essentially nonlinear the process. At the autoacceleration stage, the empiric value of energy of activation increases with increasing temperature from nearly zero to values of tens of kilocalories per mel. As the solution is cooled, the luminescence intensity continues first to rise for some time, and the plot has a negative slope. The plot becomes linear only when the reaction rate reaches a maximum. As the reaction rate decreases, the temperature dependence becomes opposite to that observed at the autoacceleration stage. The empiric values of energy of activation for the semicycles of temperature increase and decrease are the functions of reaction time. The opposite direction of these changes during the reaction indicates the irreversibility of the process at each given moment of time. At all stages, an inertness of system response to temperature variations was found.