title: Positional preferences of acetyl esterases from different CE families towards acetylated 4-O-methyl glucuronic acid-substituted xylo-oligosaccharides.
abstract: BACKGROUND
  Acetylation of the xylan backbone restricts the hydrolysis of plant poly- and oligosaccharides by hemicellulolytic enzyme preparations to constituent monosaccharides. The positional preferences and deacetylation efficiencies of acetyl esterases from seven different carbohydrate esterase (CE) families towards different acetylated xylopyranosyl units (Xylp) - as present in 4-O-methyl-glucuronic acid (MeGlcA)-substituted xylo-oligosaccharides (AcUXOS) derived from Eucalyptus globulus - were monitored by (1)H NMR, using common conditions for biofuel production (pH 5.0, 50°C).
  
  
  RESULTS
  Differences were observed regarding the hydrolysis of 2-O, 3-O, and 2,3-di-O acetylated Xylp and 3-O acetylated Xylp 2-O substituted with MeGlcA. The acetyl esterases tested could be categorized in three groups having activities towards (i) 2-O and 3-O acetylated Xylp, (ii) 2-O, 3-O, and 2,3-di-O acetylated Xylp, and (iii) 2-O, 3-O, and 2,3-di-O acetylated Xylp, as well as 3-O acetylated Xylp 2-O substituted with MeGlcA at the non-reducing end. A high deacetylation efficiency of up to 83% was observed for CE5 and CE1 acetyl esterases. Positional preferences were observed towards 2,3-di-O acetylated Xylp (TeCE1, AnCE5, and OsCE6) or 3-O acetylated Xylp (CtCE4).
  
  
  CONCLUSIONS
  Different positional preferences, deacetylation efficiencies, and initial deacetylation rates towards 2-O, 3-O, and 2,3-di-O acetylated Xylp and 3-O acetylated Xylp 2-O substituted with MeGlcA were demonstrated for acetyl esterases from different CE families at pH 5.0 and 50°C. The data allow the design of optimal, deacetylating hemicellulolytic enzyme mixtures for the hydrolysis of non-alkaline-pretreated bioenergy feedstocks.
authors: DSM Biotechnology Center, PO Box 1, 2600 MA Delft, The Netherlands ; Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands.
authors: Klaus G
authors: KG
authors: Neumüller
authors: DSM Biotechnology Center, PO Box 1, 2600 MA Delft, The Netherlands.
authors: Adriana Carvalho
authors: AC
authors: de Souza
authors: DSM Biotechnology Center, PO Box 1, 2600 MA Delft, The Netherlands.
authors: Jozef Hj
authors: JH
authors: van Rijn
authors: DSM Biotechnology Center, PO Box 1, 2600 MA Delft, The Netherlands.
authors: Hugo
authors: H
authors: Streekstra
authors: Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands.
authors: Harry
authors: H
authors: Gruppen
authors: Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands.
authors: Henk A
authors: HA
authors: Schols
keywords: Acetyl xylan esterase; Deacetylation; Hemicellulase; Positional specificity; Xylan
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