title: Purification and characterization of a feruloyl esterase from the fungus Penicillium expansum.
abstract: An extracellular phenolic acid esterase produced by the fungus Penicillium expansum in solid state culture released ferulic and rho-coumaric acid from methyl esters of the acids, and from the phenolic-carbohydrate esters O-[5-O-(trans-feruloyl)-alpha-L-arabinofuranosyl]-(1-->3)-O-beta- D-xylopyranosyl-(1-->4)-D-xylopyranose (FAXX) and O-[5-O-((E)-rho-coumaroyl)-alpha-L-arabinofuranosyl]- (1-->3)-O-beta-D-xylopyranosyl-(1-->4)-D-xylopyranose (PAXX). The esterase was purified 360-fold in successive steps involving ultrafiltration and column chromatography by gel filtration, anion exchange and hydrophobic interaction. These chromatographic methods separated the phenolic acid esterase from alpha-L-arabinofuranosidase, pectate and pectin lyase, polygalacturonase, xylanase and beta-D-xylosidase activities. The phenolic acid esterase had an apparent mass of 65 kDa under non-denaturing conditions and a mass of 57.5 kDa under denaturing conditions. Optimal pH and temperature were 5.6 and 37 degrees C, respectively and the metal ions Cu2+ and Fe3+ at concentrations of 5 mmol 1-1 inhibited feruloyl esterase activity by 95% and 44%, respectively, at the optimum pH and temperature. The apparent Km and Vmax of the purified feruloyl esterase for methyl ferulate at pH 5.6 and 37 degrees C were 2.6 mmol 1-1 and 27.1 mumol min-1 mg-1. The corresponding constants of rho-coumaroyl esterase for methyl coumarate were 2.9 mmol 1-1 and 18.6 mumol min-1 mg-1.
authors.affiliation: Food Science Division (Microbiology), Department of Agriculture for Northern Ireland, Belfast, UK.
authors.forename: J
authors.initials: J
authors.lastname: Donaghy
authors.forename: A M
authors.initials: AM
authors.lastname: McKay
mesh_terms: D002265:Carboxylic Ester Hydrolases / Q000302:isolation & purification* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010407:Penicillium / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D002265:Carboxylic Ester Hydrolases; C070196:feruloyl esterase