Abstract
CHE4โ1, a bacterial strain that belongs to the genus Acinetobacter and expresses high level of inducible extracellular cholesterol esterase (CHE), was isolated from feces of carnivore Panthera pardus var. The cholesterol esterase of the strain CHE4โ1 was purified by ultrafiltration followed with DEAEโSepharose FF chromatography and PhenylโSepharose CLโ4B chromatography, and then by Sephadex Gโ50 gel filtration. Different from other known microbial cholesterol esterase, the purified CHE from CHE4โ1 strain is a monomer with molecular weight of 6.5 kD and has high activity to both longโchain and shortโchain cholesterol ester. Enzymatic activity was enhanced in the presence of metal ion Ca^2+^, Zn^2+^ and boracic acid, and was not significantly affected by several detergents including sodium cholate, Triton X100 and Tweenโ80. The enzyme was found to be stable during longโterm aqueous storage at 4 ยฐC, indicating its potential as a clinical diagnostic reagent. To the best of our knowledge, this is the first report regarding purification and characterization of CHE from Acinetobacter sp. The results demonstrated that this particular CHE is a novel cholesterol esterase. (ยฉ 2010 WILEYโVCH Verlag GmbH & Co. KGaA, Weinheim)