Biochemical characteristics and gene cloning of a novel thermostable feruloyl esterase from Chaetomium sp.

A feruloyl esterase from Chaetomium sp. CQ31 was purified and biochemically characterized. The purified feruloyl esterase had a specific activity of 38.6 U/mg. The molecular mass of the enzyme was estimated to be 30.2 kDa by SDS-PAGE, and 29.6 kDa by gel filtration, indicating that the enzyme was a monomer. The optimum pH and temperature of the enzyme were pH 7.5 and 60 °C, respectively. It was stable over a broad pH range of 4.0–10.0, and also exhibited good thermostability. The enzyme displayed strict substrate specificity. The Km and Vmax values for methyl ferulate were 0.98 μmol/min/mg and 42.6 U/mg, respectively. Furthermore, the feruloyl esterase gene was cloned and sequenced. Open reading frame (ORF) of the feruloyl esterase gene (879-bp) encodes 274 amino acids. The deduced amino acid sequence of the feruloyl esterase gene exhibited the highest identity (79%) with that of type B feruloyl esterase from Magnaporthe oryzae.