Purification and partial characterization of two feruloyl esterases from the anaerobic fungus Neocallimastix strain MC-2

Abstract

Two extracellular feruloyl esterases (FAE-I and FAE-II) produced by the anaerobic fungus Neocallimastix strain MC-2 which cleave ferulic acid from O- {5-O-[(E)-feruloyl]-α-L-arabinofuranosyl}-(1→3)-O-β-D-xylopyranosyl- (1→4)-D-xylopyranose (FAXX) were purified. The molecular masses of FAE-I and FAE-II were 69 and 24 kDa, respectively, under both denaturing and nondenaturing conditions. Apparent K(m) and maximum rate of hydrolysis with FAXX were 31.9 μM and 2.9 μmol min-1 mg-1 for FAE-I and 9.6 μM and 11.4 μmol min-1 mg-1 for FAE-II. FAE-II was specific for FAXX, but FAE-I hydrolyzed FAXX and PAXX, the equivalent p-coumaroyl ester, at a maximum rate of metabolism ratio of 3:1.