Abstract
A. awamori feruloly esterases, termed FAE-a and FAE-b, were purified to homogeneity by ammonium sulfate fractionation, DEAE-Sephadex A-50 column chromatography, DEAE-Toyopearl 650 column chromatography, hydrophobic chromatography on Butyl Toyopearl 650S, and gel filtration on Toyopearl HW55. The molecular weights (Mr) of FAE-a and FAE-b were estimated to be 31 KDa and 29 KDa by SDS-PAGE; these isoelectric points were 3.9 and below 3.4, respectively. Both enzymes were optimally active at 45-50°C and pH 5.0-5.5. FAE-a was stable up to 37°C, and FAE-b was stable up to 50°C. Both enzymes hydrolyzed predominantly the feruloylated carbohydrate ester prepared from pineapple stem residue rather than methyl esters of ferulic acid.
