title: Purification and characterization of a thermostable esterase from the moderate thermophile Bacillus circulans.
abstract: The thermostable esterase from the moderate thermophile Bacillus circulans was purified to homogeneity using a four-step procedure. Esterase activity was associated with a protein of molecular mass 95 kDa, composed of three identical subunits of 30 kDa. The esterase activity was thermostable with a maximum activity at 55 degrees C using initial rate assay. The half-inactivation temperature was 71 degrees C after a 1-h treatment, which compared favorably to that of other enzymes. Activity at temperatures of 30-37 degrees C was high (about half of maximum), making this new enzyme very attractive for applications in this moderate temperature range. The esterase also showed high activity at a rather alkaline pH (higher than 10). The specificity pattern showed a marked specificity for mid-chain-length fatty acids (3-8 carbon atoms), which classified the enzyme as a carboxylesterase.
authors.affiliation: Biocatalysis and Fine Chemistry group, CNRS ESA 6111, Faculté des Sciences de Luminy, Marseille, France.
authors.forename: A
authors.initials: A
authors.lastname: Kademi
authors.forename: N
authors.initials: N
authors.lastname: Aït-Abdelkader
authors.forename: L
authors.initials: L
authors.lastname: Fakhreddine
authors.forename: J
authors.initials: J
authors.lastname: Baratti
mesh_terms: D001407:Bacillus / Q000201:enzymology*; D002265:Carboxylic Ester Hydrolases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability; D005227:Fatty Acids / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D004791:Enzyme Inhibitors; D005227:Fatty Acids; D002265:Carboxylic Ester Hydrolases