Esterase EstK from Pseudomonas putida mt‐2: An enantioselective acetylesterase with activity for deacetylation of xylan and poly(vinylacetate)

An extracellular esterase gene estK was identified in Pseudomonas putida mt‐2 and overexpressed at high levels in Escherichia coli . The recombinant EstK enzyme was purified and characterized kinetically against p ‐nitrophenyl ester and other aryl–alkyl ester substrates and found to be selective for hydrolysis of acetyl ester substrates with high activity for p ‐nitrophenyl acetate ( k cat 5.5 Sec −1 , K M 285 µM). Recombinant EstK was found to catalyze deacetylation of acetylated beech xylan, indicating a possible in vivo function for this enzyme, and partial deacetylation of a synthetic polymer (poly(vinylacetate)). EstK was found to catalyze enantioselective hydrolysis of racemic 1‐phenylethyl acetate, generating 1 R ‐phenylethanol with an enantiomeric excess of 80.4%.