title: The identification and partial characterisation of a novel inducible extracellular thermostable esterase from the archaeon Sulfolobus shibatae.
abstract: Extracellular esterases have so far only been reported in eubacteria, here we report the first identification and partial characterisation of a novel inducible extracellular esterase from the thermoacidophilic archaeon Sulfolobus shibatae. This esterase exhibits remarkable stability to both acid and heat. Esterase activity is induced by growth on a range of polyoxyethylenesorbitan (Tween) compounds as sole carbon source. Activity occurs over a wide temperature (25-99 degrees C) and pH (pH4.0-9.0) range and is optimal at 90 degrees C and pH6.0. It exhibits high thermal stability, with a half-life of 20 min at 120 degrees C, and shows a transient thermal activation of 60% at 90 degrees C. The thermal inactivation of function occurs by first order kinetics, and after 120 min incubation at 120 degrees C 50% of activity still remains. It is able to hydrolyse mono- and diglycerides, but is unable to hydrolyse the triglycerides olive oil and triolein, which is indicative of an esterase and not a lipase.
mesh_terms: D004790:Enzyme Induction; D004795:Enzyme Stability; D004950:Esterases / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008049:Lipase / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D011136:Polysorbates / Q000494:pharmacology; D016944:Sulfolobus / Q000201:enzymology*; D013997:Time Factors
chemical_list: D011136:Polysorbates; D004950:Esterases; D008049:Lipase