title: Kinetics of thermal inactivation of the extracellular proteinase from Pseudomonas fluorescens 22F: influence of pH, calcium, and protein.
abstract: The influence of pH, calcium ion activity, protein, and enzyme purification on the kinetics of heat inactivation of the extracellular proteinase from Pseudomonas fluorescens 22F was studied in the temperature range 80-120 degrees C. At pH 5.5-8.6 the rate of inactivation increased slightly with increasing pH values. The pH dependence of inactivation suggests that the inactivation mechanism is mainly through deamidation. Calcium ion activity had no influence on the kinetics of heat inactivation of the proteinase. Addition of 1.8% sodium caseinate to the enzyme solution slightly decreased the heat stability of the proteinase, possibly because part of the inactivation of the proteinase is caused by aggregation to casein. Purification of the proteinase did not change the rate of thermal inactivation.
authors.affiliation: Department of Food Technology and Nutritional Sciences, Food Science Group, Wageningen Agricultural University, The Netherlands.
authors.forename: E P
authors.initials: EP
authors.lastname: Schokker
authors.forename: M A
authors.initials: MA
authors.lastname: van Boekel
mesh_terms: D002122:Calcium Chloride / Q000494:pharmacology*; D002151:Calorimetry; D010450:Endopeptidases / Q000378:metabolism*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011551:Pseudomonas fluorescens / Q000201:enzymology*; D013816:Thermodynamics
chemical_list: D010450:Endopeptidases; D002122:Calcium Chloride