title: Characterization of Heterologously Expressed Acetyl Xylan Esterase1 Isolated from the Anaerobic Rumen FungusNeocallimastix frontalisPMA02.
abstract: Acetyl xylan esterase (AXE), which hydrolyzes the ester linkages of the naturally acetylated xylan and thus known to have an important role for hemicellulose degradation, was isolated from the anaerobic rumen fungusNeocallimastix frontatlisPMA02, heterologously expressed inEscherichi coli(E.coli) and characterized. The full-length cDNA encoding NfAXE1 was 1,494 bp, of which 978 bp constituted an open reading frame. The estimated molecular weight of NfAXE1 was 36.5 kDa with 326 amino acid residues, and the calculated isoelectric point was 4.54. The secondary protein structure was predicted to consist of nine α-helixes and 12 β-strands. The enzyme expressed inE.colihad the highest activity at 40°C and pH 8. The purified recombinant NfAXE1 had a specific activity of 100.1 U/mg whenp-nitrophenyl acetate (p-NA) was used as a substrate at 40°C, optimum temperature. The amount of liberated acetic acids were the highest and the lowest whenp-NA and acetylated birchwood xylan were used as substrates, respectively. The amount of xylose released from acetylated birchwod xylan was increased by 1.4 fold when NfAXE1 was mixed with xylanase in a reaction cocktail, implying a synergistic effect of NfAXE1 with xylanase on hemicellulose degradation.
authors.affiliation: InfoBoss Incorporation, Seoul 07766, Korea.|Institute of Biological Chemistry, Washington State University, Pullman, WA 99163, USA.
authors.forename: Mi
authors.initials: M
authors.lastname: Kwon
authors.affiliation: Department of Agricultural Science, Korea National Open University, Seoul 03087, Korea.|Department of Animal Sciences, Kyungpook National University, Sangju 37224, Korea.
authors.forename: Jaeyong
authors.initials: J
authors.lastname: Song
authors.affiliation: GnCBio Incorporation, Daejeon 34069, Korea.
authors.forename: Hong-Seog
authors.initials: HS
authors.lastname: Park
authors.affiliation: Department of Agricultural Science, Korea National Open University, Seoul 03087, Korea.
authors.forename: Hyunjin
authors.initials: H
authors.lastname: Park
authors.affiliation: Department of Agricultural Science, Korea National Open University, Seoul 03087, Korea.
authors.forename: Jongsoo
authors.initials: J
authors.lastname: Chang
keywords: Acetyl Xylan Esterase; Anaerobic Rumen Fungus; Hemicellulose; Neocallimastix frontalis