Structural characterization of linear isomalto-/malto-oligomer products synthesized by the novel GTFB 4,6-α-glucanotransferase enzyme from Lactobacillus reuteri 121

Justyna M. Dobruchowska, Gerrit J. Gerwig, Slavko Kralj, Pieter Grijpstra, Hans Leemhuis, Lubbert Dijkhuizen*, Johannis P. Kamerling

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

60 Citations (Scopus)

Abstract

Recently, a novel glucansucrase (GS)-like gene (gtfB) was isolated from the probiotic bacterium Lactobacillus reuteri 121 and expressed in Escherichia coli. The purified recombinant GTFB enzyme was characterized and turned out to be inactive with sucrose, the natural GS substrate. Instead, GTFB acted on malto-oligosaccharides (MOSs), thereby yielding elongated gluco-oligomers/polymers containing besides (α1→4) also (α1→6) glycosidic linkages, and it was classified as a 4,6-α-glucanotransferase. To gain more insight into its reaction specificity, incubations of the GTFB enzyme with a series of MOSs and their corresponding alditols [degree of polymerization, DP2(-ol)–DP7 (-ol)] were carried out, and (purified) products were structurally analyzed with matrix-assisted laser desorption ionization time-of-flight mass spectrometry and one-/two-dimensional 1H and 13C nuclear magnetic resonance spectroscopy. With each of the tested malto-oligomers, the GTFB enzyme yielded series of novel linear isomalto-/malto-oligomers, in the case of DP7 up to DP >35.
Original languageEnglish
Pages (from-to)517-528
Number of pages12
JournalGlycobiology
Volume22
Issue number4
DOIs
Publication statusPublished - Apr-2012

Keywords

  • alpha-d-glucans
  • glucansucrase
  • GTFB 4
  • 6-alpha-glucanotransferase
  • Lactobacillus reuteri
  • structural analysis
  • ALPHA-D-GLUCANS
  • REUTERANSUCRASE
  • SPECIFICITY
  • MECHANISM
  • MUTANT

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