Distinct roles of carbohydrate esterase family CE16 acetyl esterases and polymer-acting acetyl xylan esterases in xylan deacetylation.
Mass spectrometric analysis was used to compare the roles of two acetyl esterases (AE, carbohydrate esterase family CE16) and three acetyl xylan esterases (AXE, families CE1 and CE5) in deacetylation of natural substrates, neutral (linear) and 4-O-methyl glucuronic acid (MeGlcA) substituted xylooligosaccharides (XOS). AEs were similarly restricted in their action and apparently removed in most cases only one acetyl group from the non-reducing end of XOS, acting as exo-deacetylases. In contrast, AXEs completely deacetylated longer neutral XOS but had difficulties with the shorter ones. Complete deacetylation of neutral XOS was obtained after the combined action of AEs and AXEs. MeGlcA substituents partially restricted the action of both types of esterases and the remaining acidic XOS were mainly substituted with one MeGlcA and one acetyl group, supposedly on the same xylopyranosyl residue. These resisting structures were degraded to great extent only after inclusion of α-glucuronidase, which acted with the esterases in a synergistic manner. When used together with xylan backbone degrading endoxylanase and β-xylosidase, both AE and AXE enhanced the hydrolysis of complex XOS equally.
['Koutaniemi|S|S|', 'van Gool|M P|MP|', 'Juvonen|M|M|', 'Jokela|J|J|', 'Hinz|S W|SW|', 'Schols|H A|HA|', 'Tenkanen|M|M|']
D000107:Acetylation D000115:Acetylesterase D001234:Aspergillus niger D043364:Endo-1,4-beta Xylanases D005965:Glucuronates D006026:Glycoside Hydrolases D006868:Hydrolysis D009844:Oligosaccharides D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization D013379:Substrate Specificity D014990:Xylans
carbohydrate esterase CE16 acetyl esterase acetyl esterase Acetyl xylan esterase Acetyl xylan esterase AE AXE 4-O-methyl glucuronic acid Ac AcUXOS AcXOS CE GH HPAEC-PAD Mass spectrometry O-acetyl O-acetylated acidic MeGlcA-substituted xylooligosaccharides O-acetylated neutral xylooligosaccharides Xylan acetylation acetyl xylan esterase glycoside hydrolase high performance anion exchange chromatography with pulsed amperometric detection