A Bacillus licheniformis pectin acetylesterase is specific for homogalacturonans acetylated at O-3.
A recombinant acetylesterase from Bacillus licheniformis DSM13, belonging to carbohydrate esterase family 12, was purified and biochemically characterized. The purified enzyme, termed BliPAE, was capable of deacetylating acetylated pectins, e.g. sugar beet pectin (SBP). Contrary to its provisional annotation as rhamnogalacturonan acetylesterase, the enzyme specifically removed acetyl groups from the homogalacturonan region classifying it as a PAE. The recombinant enzyme has a molecular mass of 26.7 kDa and shows optimal activity at pH 8.0 and 50°C. It is stable in the range pH 5.0-7.0 and below 50°C. Methylesterification of the galacturonic acid (GalA) moieties reduces the deacetylation efficacy of BliPAE. The enzyme efficiently removes acetyl groups from SBPs with low degree of methylesterification (DM) 9-30, releasing about 75% of the acetyl groups present in the homogalacturonan. Furthermore, (1)H NMR of polymer and LC-HILIC-MS(n) after endo-PGII and PL degradation were used to structurally characterize the BliPAE-modified pectins. The results show that BliPAE removes acetyl groups specifically when substituted at the O-3 position of GalA moieties.
Wageningen University, Laboratory of Food Chemistry, Postbus 17, Wageningen 6700 AA The Netherlands.
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Remoroza
Westphalian Wilhelms-University of Münster, Department of Plant Biology and Biotechnology, Schlossplatz 8, Münster 48143 Germany.
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Wagenknecht
Wageningen University, Laboratory of Food Chemistry, Postbus 17, Wageningen 6700 AA The Netherlands.
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Gu
DuPont Nutrition Biosciences ApS, Edwin Rahrsvej 38, Brabrand DK-8220 Denmark.
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Buchholt
Westphalian Wilhelms-University of Münster, Department of Plant Biology and Biotechnology, Schlossplatz 8, Münster 48143 Germany.
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Moerschbacher
Wageningen University, Laboratory of Food Chemistry, Postbus 17, Wageningen 6700 AA The Netherlands.
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Schols
Wageningen University, Laboratory of Food Chemistry, Postbus 17, Wageningen 6700 AA The Netherlands. Electronic address: harry.gruppen@wur.nl.
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Gruppen
D000107:Acetylation; D001407:Bacillus / Q000201:enzymology*; D004795:Enzyme Stability; D004950:Esterases / Q000737:chemistry / Q000378:metabolism*; D004951:Esterification; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D010368:Pectins / Q000737:chemistry* / Q000378:metabolism*; D013379:Substrate Specificity; D013696:Temperature
D010368:Pectins; D004950:Esterases; C100533:pectinacetylesterase; C003181:polygalacturonic acid
Endo-polygalacturonase; HILIC-MS/ELSD; NMR; Pectin lyase; Sugar beet pectin