Browsing by Autor "Patrick Adlercreutz"

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    A novel glycoside hydrolase 43-like enzyme from <i>Clostridium boliviensis</i> is an endo-xylanase and a candidate for xylooligosaccharide production from different xylan substrates
    (American Society for Microbiology, 2024) Daniel Martín Salas-Veizaga; Leonardo Roberto Rocabado-Villegas; Javier A. Linares‐Pastén; Elísabet Eik Guðmundsdóttir; Guðmundur Ó. Hreggviðsson; María Teresa Álvarez Aliaga; Patrick Adlercreutz; Eva Nordberg Karlsson
    The genome of <i>Clostridium boliviensis</i> strain E-1 encodes a number of hypothetical enzymes, annotated as glycoside hydrolase-like but not classified in the Carbohydrate Active Enzyme Database (CAZy). A novel thermostable GH43-like enzyme is here characterized as an endo-β-xylanase of interest in the production of prebiotic xylooligosaccharides (XOs) from different xylan sources. <i>CbE1</i>Xyn43-l is a two-domain enzyme composed of a catalytic GH43-l domain and a CBM6 domain, producing xylotriose as main XO product. The enzyme has homologs in many related <i>Clostridium</i> strains which may indicate a similar function and be a previously unknown type of endo-xylanase in this evolutionary lineage of microorganisms.
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    Extraction of Glucuronoarabinoxylan from Quinoa Stalks (<i>Chenopodium quinoa</i> Willd.) and Evaluation of Xylooligosaccharides Produced by GH10 and GH11 Xylanases
    (American Chemical Society, 2017) Daniel Martín Salas-Veizaga; Rodrigo Villagomez; Javier A. Linares‐Pastén; Cristhian Carrasco; María Teresa Álvarez; Patrick Adlercreutz; Eva Nordberg Karlsson
    Byproducts from quinoa are not yet well explored sources of hemicellulose or products thereof. In this work, xylan from milled quinoa stalks was retrieved to 66% recovery by akaline extraction using 0.5 M NaOH at 80 °C, followed by ethanol precipitation. The isolated polymer eluted as a single peak in size-exclusion chromatography with a molecular weight of >700 kDa. Analysis by Fourier transform infrared spectroscopy and nuclear magnetic resonance (NMR) combined with acid hydrolysis to monomers showed that the polymer was built of a backbone of β(1 → 4)-linked xylose residues that were substituted by 4-O-methylglucuronic acids, arabinose, and galactose in an approximate molar ratio of 114:23:5:1. NMR analysis also indicated the presence of α(1 → 5)-linked arabinose substituents in dimeric or oligomeric forms. The main xylooligosaccharides (XOs) produced after hydrolysis of the extracted glucuronoarabinoxylan polymer by thermostable glycoside hydrolases (GHs) from families 10 and 11 were xylobiose and xylotriose, followed by peaks of putative substituted XOs. Quantification of the unsubstituted XOs using standards showed that the highest yield from the soluble glucuronoarabinoxylan fraction was 1.26 g/100 g of xylan fraction, only slightly higher than the yield (1.00 g/100 g of xylan fraction) from the insoluble fraction (p < 0.05). No difference in yield was found between reactions in buffer or water (p > 0.05). This study shows that quinoa stalks represent a novel source of glucuronoarabinoxylan, with a substituent structure that allowed for limited production of XOs by GH10 or GH11 enzymes.