title: Characterization of an acetyl esterase from Myceliophthora thermophila C1 able to deacetylate xanthan.
abstract: Screening of eight carbohydrate acetyl esterases for their activity towards xanthan resulted in the recognition of one active esterase. AXE3, a CAZy family CE1 acetyl xylan esterase originating from Myceliophthora thermophila C1, removed 31% of all acetyl groups present in xanthan after a 48 h incubation. AXE3 activity towards xanthan was only observed when xanthan molecules were in the disordered conformation. Optimal performance towards xanthan was observed at 53 °C in the complete absence of salt, a condition favouring the disordered conformation. AXE3-deacetylated xanthan was hydrolyzed using cellulases and analyzed for its repeating units using UPLC-HILIC-ELSD/ESI-MS. This showed that AXE3 specifically removes the acetyl groups positioned on the inner mannose and that acetyl groups positioned on the outer mannose are not removed at all. After a prolonged incubation at optimal conditions, 57% of all acetyl groups, representing 70% of all acetyl groups on the inner mannose units, were hydrolyzed.
authors.affiliation: Wageningen University, Laboratory of Food Chemistry, PO Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Marijn M
authors.initials: MM
authors.lastname: Kool
authors.affiliation: Wageningen University, Laboratory of Food Chemistry, PO Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Henk A
authors.initials: HA
authors.lastname: Schols
authors.affiliation: Westfälische Wilhelms Universität, Department of Plant Biology and Biotechnology, Schlossplatz 8, 48143 Münster, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Wagenknecht
authors.affiliation: Dyadic Netherlands, Nieuwe Kanaal 7-S, 6709 PA Wageningen, The Netherlands.
authors.forename: Sandra W A
authors.initials: SW
authors.lastname: Hinz
authors.affiliation: Westfälische Wilhelms Universität, Department of Plant Biology and Biotechnology, Schlossplatz 8, 48143 Münster, Germany.
authors.forename: Bruno M
authors.initials: BM
authors.lastname: Moerschbacher
authors.affiliation: Wageningen University, Laboratory of Food Chemistry, PO Box 17, 6700 AA Wageningen, The Netherlands. Electronic address: harry.gruppen@wur.nl.
authors.forename: Harry
authors.initials: H
authors.lastname: Gruppen
mesh_terms: D000107:Acetylation; D000115:Acetylesterase / Q000737:chemistry*; D001203:Ascomycota / Q000201:enzymology*; D006868:Hydrolysis; D011135:Polysaccharides, Bacterial / Q000737:chemistry*
chemical_list: D011135:Polysaccharides, Bacterial; D000115:Acetylesterase; C002563:xanthan gum
keywords: AXE3; Enzymatic deacetylation; Position of acetyl groups; Xanthan conformation