Experimental modelling of thermal inactivation of urease.
Thermal inactivation of jack bean urease (EC 3.5.1.5) was investigated in a 0.1 M phosphate buffer with pH 7. An injection flow calorimetry method was adapted for the measurement of the enzyme activity. The inactivation curves were measured in the temperature range of 55 to 87.5 degrees C. The curves exhibited a biphasic pattern in the whole temperature range and they were well fitted with a biexponential model. A simultaneous fit of all inactivation data was based on kinetic models that were derived from different inactivation mechanisms and comprised the material balances of several enzyme forms and the enthalpy balance characterizing the initial heating period of enzyme solution. The multitemperature evaluation revealed that an adequate model had to incorporate at least three reaction steps. It was concluded that the key reaction steps at urease thermal inactivation were the reversible dissociation/denaturation of native form into an inactive denatured form, and irreversible association reactions of both the denatured and native forms.
Illeová
Viera
V
Department of Chemical and Biochemical Engineering, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 812 37 Bratislava, Slovak Republic.
Polakovic
Milan
M
Stefuca
Vladimír
V
Acai
Pavel
P
Juma
Mohammad
M
D002151:Calorimetry / Q000379:methods*; D006358:Hot Temperature; D007700:Kinetics; D008433:Mathematics; D008956:Models, Chemical; D013816:Thermodynamics; D014510:Urease / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism
D014510:Urease