caa a22 4500 605499799 CHVBK 20210128100552.0 cr unu---uuuuu 210128e20150501xx s 000 0 eng 10.1007/s00253-014-6160-2 doi (NATIONALLICENCE)springer-10.1007/s00253-014-6160-2 Redistribution of acetyl groups on the non-reducing end xylopyranosyl residues and their removal by xylan deacetylases [Elektronische Daten] [Vladimír Puchart, Peter Biely] Background: Monoacetylated xylosyl residues of the main hardwood hemicellulose acetylglucuronoxylan undergo acetyl group migration between positions 2 and 3, and predominantly to position 4 of the non-reducing end xylopyranosyl (NRE-Xylp) residues which are amplified by saccharifying enzymes. On monoacetylated non-reducing end xylopyranosyl (NRE-Xylp) residues of xylooligosaccharides the acetyl group migrates predominantly to position 4 and hinders their hydrolysis by β-xylosidase. Methods: Acetyl migration on the NRE-Xylp residues and their enzymatic deacetylation by various xylan deacetylases was followed by 1H-NMR spectroscopy and TLC. Results: A 5-min heat treatment of 4-nitrophenyl 3-O-acetyl-β-D-xylopyranoside was sufficient to establish equilibrium between monoacetate derivatives acetylated at positions 2, 3 and 4. Rapid acetyl migration along the NRE-Xylp ring at elevated temperature was confirmed in derivatives of methyl β-1,4-xylotrioside (Xyl3Me) monoacetylated solely on the NRE-Xylp residue, the analogues of naturally occurring acetylated xylooligosaccharides. The Xyl3Me monoacetates were used as substrates to study regioselectivity of the NRE-Xylp residue deacetylation by various acetylxylan esterases (AcXEs) of distinct carbohydrate esterase (CE) families. CE1, CE4 and CE6 AcXEs hydrolyzed considerably faster the 2″-O-acetyl derivative than the 3″-O-acetyl derivative. In contrast, the CE16 acetyl esterase preferred to attack the ester bond at position 3 followed by position 4. Conclusions: Redistribution of acetyl group on the NRE-Xylp residues is extremely rapid at elevated temperature and includes the formation of 4-acetate. Regioselectivity of AcXEs and CE16 acetyl esterase on these monoacetates is complementary. General significance: The formation of all isomers of acetylated xylosyl residues must be taken into account after a long-term incubation of acetylxylan and acetylated xylooligosaccharides solutions or upon their treatment at elevated temperatures. This phenomenon emphasizes requirement of both types of xylan deacetylases to enable a rapid saccharification of xylooligosaccharides by glycoside hydrolases. Springer-Verlag Berlin Heidelberg, 2014 Xylooligosaccharide deacetylation nationallicence Regioselectivity nationallicence Acetylxylan esterase nationallicence Non-reducing end deacetylase nationallicence Monoacetates of methyl β-1,4-xylotrioside nationallicence Acetyl group migration nationallicence CE : Carbohydrate esterase nationallicence AcXE : Acetylxylan esterase nationallicence AcE : Acetyl esterase nationallicence Xyl3Me : Methyl β-D-xylopyranosyl-1,4-β-D-xylopyranosyl-1,4-β-D-xylopyranoside, methyl β-D-xylotrioside nationallicence Xyl p : β-D-xylopyranosyl nationallicence MeGlcA : 4-O-methyl-α-D-glucuronic acid nationallicence Puchart Vladimír Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 38, Bratislava, Slovak Republic aut Biely Peter Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 38, Bratislava, Slovak Republic aut Applied Microbiology and Biotechnology Springer Berlin Heidelberg 99/9(2015-05-01), 3865-3873 0175-7598 99:9<3865 2015 99 253 https://doi.org/10.1007/s00253-014-6160-2 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00253-014-6160-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Puchart Vladimír Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 38, Bratislava, Slovak Republic aut NATIONALLICENCE 700 1- Biely Peter Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 38, Bratislava, Slovak Republic aut NATIONALLICENCE 773 0- Applied Microbiology and Biotechnology Springer Berlin Heidelberg 99/9(2015-05-01), 3865-3873 0175-7598 99:9<3865 2015 99 253