Mode of action of xylogalacturonan hydrolase towards xylogalacturonan and xylogalacturonan oligosaccharides

J.S. Zandleven, G. Beldman, M. Bosveld, J.A.E. Benen, A.G.J. Voragen

Research output: Contribution to journalArticleAcademicpeer-review

25 Citations (Scopus)

Abstract

XGH (xylogalacturonan hydrolase; GH 28) is an enzyme that is capable of degrading XGA (xylogalacturonan), which is a polymer of ¿-D-galacturonic acid, highly substituted with ß-D-xylose. XGA is present in cell walls of various plants and exudates, such as gum tragacanth. XGA oligosaccharides were derived from an XGH digestion of gum tragacanth, then fractionated, and analysed for their sugar composition and structure by matrix-assisted laser-desorption ionization-time-of-flight MS and nanospray MS. Several oligosaccharides from XGA were identified with different galacturonic acid/xylose ratios including five oligosaccharide isomers. Although XGH can act as an endo-enzyme, product-progression profiling showed that the disaccharide GalAXyl was predominantly produced from XGA by XGH, which indicated also an exolytic action. The latter was further supported by degradation studies of purified oligosaccharide GalA4Xyl3. It was shown that XGH acted from the non-reducing end towards the reducing end of this oligosaccharide, and showed the processive character of XGH. The results from this study further show that although XGH prefers to act between two xylosidated GalA units, it tolerates unsubstituted GalA units in its - 1 and + 1 subsites.
Original languageEnglish
Pages (from-to)719-725
JournalBiochemical Journal
Volume387
Issue number3
DOIs
Publication statusPublished - 2005

Keywords

  • degrade xylogalacturonan
  • aspergillus-aculeatus
  • glycoside hydrolases
  • exopolygalacturonase
  • oligogalacturonides
  • classification
  • purification
  • enzymes
  • niger

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