A thermostable metalloprotease, produced from an environmental strain of Candida kefyr 41 PSB, was purified 16 fold with a 60% yield by cold ethanol precipitation and affinity chromatography (bentoniteacrylamide-cysteine microcomposite). The purified enzyme appeared as a single protein band at 43 kDa. Its optimum pH and temperature points were found to be 7.0 and 105 degrees C, respectively. K-m and V-max values of the enzyme were determined to be 3.5 mg/mL and 4.4 mu mol mL(-1) min(-1), 1.65 mg/mL and 6.1 mu mol mL(-1) min(-1), using casein and gelatine as the substrates, respectively. The activity was inhibited by using ethylenediamine tetraacetic acid (EDTA), indicating that the enzyme was a metalloprotease. Stability of the enzyme was investigated by using thermodynamic and kinetic parameters. The thermal inactivation profile of the enzyme conformed to the first order kinetics. The half life of the enzyme at 95, 105, 115, 125 and 135 degrees C was 1310, 610, 220, 150, and 86 min, respectively. (C) 2016 Elsevier B.V. All rights reserved.