DIFFERENTIAL SCANNING CALORIMETRY OF THE IRREVERSIBLE THERMAL-DENATURATION OF CELLULASE FROM STREPTOMYCES-HALSTEDII JM8

High sensitivity differential scanning calorimetry has been applied to characterize the irreversible thermal denaturation of a cellulase, as suming that thermal denaturation takes place according to the kinetic scheme [GRAPHICS] where k is a first-order kinetic constant that chang es with temperature, as given by the Arrhenius equation; N the native state, and D the denatured one. On the basis of this model, the values of the rate constant as a function of temperature and the activation energy were calculated. The analytical data obtained with the fluoresc ence method as well by measurement of the enzymatic activity temperatu re dependence support this two-state kinetic model.