Step-wise enzymatic preparation and structural characterization of singly and doubly substituted arabinoxylo-oligosaccharides with non-reducing end terminal branches.
Pastell, H., Tuomainen, P., Virkki, L. & Tenkanen, M. (2008). Carbohydrate Research, 343(18), 3049-3057.
Shearzyme (GH10 endo-1,4-β-D-xylanase) and two different α-L-arabinofuranosidases (AXH-m and AXH-d3) were used stepwise to manufacture arabinoxylo-oligosaccharides (AXOS) with α-L-Araf (1→2)-monosubstituted β-D-Xylp residues or α-L-Araf (1→2)- and (1→3) doubly substituted β-D-Xylp residues from wheat arabinoxylan (AX) in a rather straightforward way. Four major AXOS (d-I, d-II, m-I and m-II) were formed in two separate hydrolyses. The AXOS were purified and the structures were confirmed using TLC, HPAEC-PAD, MALDI-TOF-MS and 1D and 2D NMR spectroscopy. The samples were identified as d-I: α-L-Araf-(1→2)-[α-L-Araf-(1→3)]-β-D-Xylp-(1→4)-β-D-Xylp-(1→4)-D-Xylp, d-II: α-L-Araf-(1→2)-[α-L-Araf-(1→3)]-β-D-Xylp-(1→4)-D-Xylp, m-I: α-L-Araf-(1→2)-β-D-Xylp-(1→4)-β-D-Xylp-(1→4)-D-Xylp and m-II: α-L-Araf-(1→2)-β-D-Xylp-(1→4)-D-Xylp. To our knowledge, this is the first report on structural 1H and 13C NMR analysis of xylobiose-derived AXOS d-II and m-II. The latter compound has not been reported previously. The doubly substituted AXOS were produced for the first time in good yields, as d-I and d-II corresponded to 11.8 and 5.6 wt% of AX, respectively. Singly α-L-Araf (1→2)-substituted AXOS could also be prepared in similar yields by treating the doubly substituted AXOS further with AXH-d3.
Characterisation by 1H NMR spectroscopy of oligosaccharides derived from alkali-extractable wheat-flour arabinoxylan by digestion with endo-(1→4)-β-D-xylanase III from Aspergillus awamori.
Kormelink, F. J. M., Hoffmann, R. A., Gruppen, H., Voragen, A. G. J., Kamerling, J. P. & Vliegenthart, J. F. G. (1993). Carbohydrate Research, 249(2), 369-382.
Alkali-extractable wheat-flour arabinoxylan, treated with endo-(1→4)-β-D-xylanase III from Aspergillus awamori CMI 142717, was fractionated by Bio-Gel P-2 size exclusion chromatography at 60°C. Column fractions, corresponding to oligosaccharides with degrees of polymerisation from 5 to 10, were collected, and subfractionated by high performance anion-exchange chromatography on CarboPac PA-1. The structures of the oligosaccharides thus obtained were elucidated by 1H NMR spectroscopy, showing chains of (1→4)-linked β-D-xylopyranosyl residues differently substituted at O-3 and / or O-2,3 with α-L-arabinofuranosyl groups. The structures were different from those obtained with endo-(1→4)-β-D-xylanase I of the same xylanolytic enzyme system.
Characterisation by 1H-n.m.r. spectroscopy of oligosaccharides, derived from arabinoxylans of white endosperm of wheat...
Hoffmann, R. A., Leeflang, B. R., de Barse, M. M., Kamerling, J. P. & Vliegenthart, J. F. (1991). Carbohydrate Research, 221, 63-81.
Characterisation by 1H-n.m.r. spectroscopy of oligosaccharides, derived from arabinoxylans of white endosperm of wheat, that contain the elements ----4)[alpha-L-Araf-(1----3)]-beta-D-Xylp-(1---- or ----4)[alpha- L-Araf-(1----2)][alpha-L-Araf-(1----3)]-beta-D-Xylp-(1----. The structure of penta- to hepta-saccharides, generated by digestion of purified wheat-endosperm arabinoxylan with endo-(1----4)-beta-D-xylanase and isolated by gel-permeation chromatography on Bio-Gel P-6 followed by high-performance anion-exchange chromatography with pulsed amperometric detection, was established using monosaccharide and methylation analysis, f.a.b.-m.s., and 1H-n.m.r. spectroscopy. The oligosaccharides had a core of (1----4)-linked beta-D-xylopyranosyl residues 3- or 2,3-substituted with single alpha-L-arabinofuranosyl groups, and gave 1H-n.m.r. spectra typical for each type.
Simultaneous production of endo-β-1,4-xylanase and branched xylooligosaccharides by Thermomyces lanuginosus.
Puchart, V & Biely, P. (2008). Journal of Biotechnology. 137(1-4), 34–43.
When grown on beech-wood glucuronoxylan, two strains of the thermophilic fungus Thermomyces lanuginosius, IMI 84400 and IMI 96213, secreted endo-β-1,4-xylanase of glycoside hydrolase family 11 and simultaneously accumulated an acidic pentasaccharide in the medium. The aldopentaouronic acid was purified and its structure was established by a combination of NMR spectroscopy and enzyme digestion with glycosidases as MeGlcA3Xyl4. Both strains showed limited growth on wheat arabinoxylan as a carbon source. An essential part of the polysaccharide was not utilized, and it was converted to a series of arabinoxylooligosaccharides differing in the degree of polymerization. The structure of the shorter arabinoxylooligosaccharides remaining in the wheat arabinoxylan-spent medium was established using mass spectrometry and digestion with glycosidases. Xylose and linear β-1,4-xylooligosaccharides generated extracellularly during growth on either hardwood or cereal xylan were efficiently taken up by the cells and metabolized intracellularly. The data suggest that due to a lack of extracellular β-xylosidase, α-glucuronidase, and α-L-arabinofuranosidase, the widely used T. lanuginosus strains might become efficient producers of branched xylooligosaccharides from both types of xylans.
Fermentation of Plant Cell Wall Derived Polysaccharides and Their Corresponding Oligosaccharides by Intestinal Bacteria.
Van Laere, K. M. J., Hartemink, R., Bosveld, M., Schols, H. A. & Voragen, A. G. J. (2000). Journal of Agricultural and Food Chemistry, 48(5), 1644–1652.
New types of nondigestible oligosaccharides were produced from plant cell wall polysaccharides, and the fermentation of these oligosaccharides and their parental polysaccharides by relevant individual intestinal species of bacteria was studied. Oligosaccharides were produced from soy arabinogalactan, sugar beet arabinan, wheat flour arabinoxylan, polygalacturonan, and rhamnogalacturonan fraction from apple. All of the tested substrates were fermented to some extent by one or more of the individual species of bacteria tested. Bacteroides spp. are able to utilize plant cell wall derived oligosaccharides besides their reported activity toward plant polysaccharides. Bifidobacterium spp. are also able to utilize the rather complex plant cell wall derived oligosaccharides in addition to the bifidogenic fructooligosaccharides. Clostridium spp., Klebsiella spp., and Escherichia coli fermented some of the selected substrates in vitro. These studies do not allow prediction of the fermentation in vivo but give valuable information on the fermentative capability of the tested intestinal strains.
Characterization of the arabinoxylan-degrading machinery of the thermophilic bacterium Herbinix hemicellulosilytica—six new xylanases, three arabinofuranosidases and one xylosidase.
Mechelke, M., Koeck, D. E., Broeker, J., Roessler, B., Krabichler, F., Schwarz, W. H., Zverlov, V. V. & Liebl, W. (2017). Journal of Biotechnology, In Press.
Herbinix hemicellulosilytica is a newly isolated, gram-positive, anaerobic bacterium with extensive hemicellulose-degrading capabilities obtained from a thermophilic biogas reactor. In order to exploit its potential as a source for new industrial arabinoxylan-degrading enzymes, six new thermophilic xylanases, four from glycoside hydrolase family 10 (GH10) and two from GH11, three arabinofuranosidases (1x GH43, 2x GH51) and one β-xylosidase (GH43) were selected. The recombinantly produced enzymes were purified and characterized. All enzymes were active on different xylan-based polysaccharides and most of them showed temperature-vs-activity profiles with maxima around 55–65°C. HPAEC-PAD analysis of the hydrolysates of wheat arabinoxylan and of various purified xylooligosaccharides (XOS) and arabinoxylooligosaccharides (AXOS) was used to investigate their substrate and product specificities: among the GH10 xylanases, XynB showed a different product pattern when hydrolysing AXOS compared to XynA, XynC, and XynD. None of the GH11 xylanases was able to degrade any of the tested AXOS. All three arabinofuranosidases, ArfA, ArfB and ArfC, were classified as type AXH-m,d enzymes. None of the arabinofuranosidases was able to degrade the double-arabinosylated xylooligosaccharides XA2+3XX. β-Xylosidase XylA (GH43) was able to degrade unsubstituted XOS, but showed limited activity to degrade AXOS.