Characterization of a new thermophilic and acid tolerant esterase from Thermotoga maritima capable of hydrolytic resolution of racemic ketoprofen ethyl ester

A gene coding for a putative thermostable esterase (Tm1160) from the hyperthermophilic bacterium Thermotoga maritima was cloned and expressed in Escherichia coli. The purified enzyme displayed optimal activity at 70 degrees C and had a half-life of 60 min at 90 degrees C. It was stable over a range of pHs from 5.0 to 7.5 with an optimum around 5.0-5.5. The enzyme was found to have high acid tolerance and maintained about 50% of its activity even after 60 min of treatment at pH 4.5 and 70 degrees C. Furthermore, the enzyme exhibited the highest specific activity with p-nitrophenyl butyrate (318 +/- 7 s(-1) mM(-1)). Under native conditions, Tm1160 forms a similar to 74 kDa dimer in solution. In addition, the esterase Tm1160 could enantioselectively hydrolyze the racemic ketoprofen ethyl ester and with an enantiomeric excess (ee(p)) of 91.4% at a conversion of 41.1%, which makes it as a promising biocatalyst for the chiral resolution of (S)-ketoprofen. (C) 2012 Elsevier B.V. All rights reserved.