Abstract: In this study, a novel esterase was purified from the liver of blue round scads via ammonium sulfate fractionation followed by a series of column chromatographies on Q-Sepharose, Q-HP, Phenyl Fast Flow and Superdex G75 with a recovery of 0.69% and 1 150-fold purification factor. The esterase was a monomer with a molecular mass of 61.18 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Superdex G75 column chromatography. Peptide mass fingerprint analysis showed that the peptides showed a similarity of 100% to the predicted fatty acyl-CoA hydrolase precursor from Takifugu rubripes with 14 amino acid residues. The esterase showed an optimal activity at pH 8.0 and 50 ℃, and was comparably stable at pH 6.0–10.0 and 4–40 ℃. The metal ions K+, Zn2+, Cu2+, Al3+ and Fe2+ strongly suppressed the esterase activity while Ba2+, Ca2+, Mn2+, Co2+ and Mg2+ showed obvious activation effect on the enzyme’s activity. Moreover, the esterase exhibited strong tolerance against methanol, ethanol, acetone and isopropanol, as well as salt. Interestingly, the esterase preferably hydrolyzed esters with short carbon chain in aqueous solution, and exhibited hydrolytic activity toward long-chain esters in an emulsion system but not in aqueous solution. The results indicated that the esterase has both esterase and lipase activity.

Key words: blue round scads; liver; esterase; purification; characterization