Thermal deactivation kinetics of CM-cellulase from a local isolate of Aspergillus niger (RD-2231)
Demerdash, M.; Attia, R.M.
Zentralblatt für Mikrobiologie 147(7): 477-482
1992
ISSN/ISBN: 0232-4393 PMID: 1441773 Document Number: 390896
The enzyme proved more stable in temp. < 40 degrees C. The rates of activity decay were significant at high temp. and could be described as a first-order kinetic model. Deactivation rate constants (Kd) were determined at different temp. (30, 40, 55 and 65 degrees C). Kd value for CMC-ase activity decay at 65 degrees C was 28 times higher than its value at 30 degrees C. An Arrhenius type temp. dependence of Kd was found, and the activation energy (Ea) of the thermal deactivation was calculated to be 8400 cal/mole. Thermodynamic quantities ( Delta H) and ( Delta S) for deactivation process were 7700 and 11.9 cal/mole, resp. The change of 2 kinetic parameters, i.e. Vmax and Km under deactivation conditions was discussed.