title: Structural characterization of linear isomalto-/malto-oligomer products synthesized by the novel GTFB 4,6-α-glucanotransferase enzyme from Lactobacillus reuteri 121.
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 (1)H and (13)C 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.
authors.affiliation: Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.
authors.forename: Justyna M
authors.initials: JM
authors.lastname: Dobruchowska
authors.forename: Gerrit J
authors.initials: GJ
authors.lastname: Gerwig
authors.forename: Slavko
authors.initials: S
authors.lastname: Kralj
authors.forename: Pieter
authors.initials: P
authors.lastname: Grijpstra
authors.forename: Hans
authors.initials: H
authors.lastname: Leemhuis
authors.forename: Lubbert
authors.initials: L
authors.lastname: Dijkhuizen
authors.forename: Johannis P
authors.initials: JP
authors.lastname: Kamerling
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002852:Chromatography, Ion Exchange; D005936:Glucans / Q000737:chemistry; D005964:Glucosyltransferases / Q000737:chemistry*; D006031:Glycosylation; D052200:Limosilactobacillus reuteri / Q000201:enzymology*; D009682:Magnetic Resonance Spectroscopy; D008320:Maltose / Q000737:chemistry*; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013402:Sugar Alcohols / Q000737:chemistry; D014312:Trisaccharides / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D005936:Glucans; D009844:Oligosaccharides; D011994:Recombinant Proteins; D013402:Sugar Alcohols; D014312:Trisaccharides; C031146:maltoheptaose; C008317:maltotriose; D008320:Maltose; D005964:Glucosyltransferases