[On the effect of immune and normal sera on catalase]

Effect of specific immune and normal sera on catalase was studied. The sera activated the enzyme, partially protected catalase against UV-irradiation and heating and also against the effect of inhibitors. Antibodies against catalase were observed in the fraction of 7 S gamma-globulins of immune serum. In studies of heat denaturation of catalase the stabilizing effect of immune serum was more distinct than the influence of normal serum and its protein fractions. In presence of serum protein fractions there was a correlation between the enthalpy of heat denaturation of catalase and decrease in specificity of the protein, in respect to the enxyme, associated with it in a complex. Alterations in enthropy compensated completely the decrease in enthalpy.