In this study, we report the characterization of a protein from Aspergillus oryzae, exhibiting sequence identity with paraben esterase from the genus Aspergillus. The coding region of 1,586 bp, including a 77-bp intron, encoded a protein of 502 amino acids. The gene without the signal peptide of 19 amino acids was cloned into a vector, pPICZalphaC, and expressed successfully in Pichia pastoris as an active extracellular protein. The purified recombinant protein had pH and temperature optima of 7.0-8.0 and 30 degrees C, respectively, and was stable at the pH range of 7.0-10.0 and up to 40 degrees C. The optimal substrate for hydrolysis by the purified recombinant protein, among a panel of alpha-naphthyl esters (C2-C16), was alpha-naphthyl butyrate (C4), with activity of 0.16 units/mg protein. The considerable hydrolytic activity of the purified recombinant enzyme toward tributyrin was determined. However, no paraben esterase activity was detected toward the ethyl, propyl, and butyl esters of 4-hydroxybenzoic acid. In addition, no activity was detected toward the methyl esters of ferulic, p-coumaric, caffeic, and sinapic acids that would indicate feruloyl esterase activity.
