Substrate specificity of novel GH16 endo-β-(1→3)-galactanases acting on linear and branched β-(1→3)-1 galactooligosaccharides

Panagiota Kalomoiri, Jesper Holck, Laure Coulomb, Irene Boos, Kasper Enemark-Rasmussen, Nikolaj Spodsberg, Rune Nygaard Monrad, Mads Hartvig Clausen*

*Corresponding author for this work

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Arabinogalactan proteins are proteoglycans located in the plant cell wall. Most arabinogalactan proteins are composed of carbohydrate moieties of β-(1→3)-galactan main chains with β-(1→6)-galactan side chains terminated by other glycans. In this study, three novel endo-β-(1→3)-galactanases were identified and the substrate specificity was further studied using well-defined galactan oligomers. Linear and branched β-(1→3)-linked galactans, which resemble the carbohydrate core of the arabinogalactan protein, were used for the characterization of endo-β-(1→3)-galactanases. The identified enzymes required at least three consecutive galactose residues for activity. Non-substituted regions were preferred, but substituents in the -2 and +2 and in some cases also -1 and +1 subsites were tolerated to some extent, depending on the branching pattern, however at a significantly lower rate/frequency.
Original languageEnglish
JournalJournal of Biotechnology
Pages (from-to)44-52
Publication statusPublished - 2019


  • β-(1→3)-galactanases
  • Gum arabic
  • β-(1→3)-galactan
  • Type II arabinogalactan
  • Glycosyl hydrolase (GH) family 16

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