title: Structural analysis of rebaudioside A derivatives obtained by Lactobacillus reuteri 180 glucansucrase-catalyzed trans-α-glucosylation.
abstract: The wild-type Gtf180-ΔN glucansucrase enzyme from Lactobacillus reuteri 180 was found to catalyze the α-glucosylation of the steviol glycoside rebaudioside A, using sucrose as glucosyl donor in a transglucosylation process. Structural analysis of the formed products by MALDI-TOF mass spectrometry, methylation analysis and NMR spectroscopy showed that rebaudioside A is specifically α-d-glucosylated at the steviol C-19 β-d-glucosyl moiety (55% conversion). The main product is a mono-(α1 → 6)-glucosylated derivative (RebA-G1). A series of minor products, up to the incorporation of eight glucose residues, comprise elongations of RebA-G1 with mainly alternating (α1 → 3)- and (α1 → 6)-linked glucopyranose residues. These studies were carried out in the context of a program directed to the improvement of the taste of steviol glycosides via enzymatic modification of their naturally occurring carbohydrate moieties.
authors.affiliation: Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands; NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
authors.forename: Gerrit J
authors.initials: GJ
authors.lastname: Gerwig
authors.affiliation: Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands.
authors.forename: Evelien M
authors.initials: EM
authors.lastname: Te Poele
authors.affiliation: Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands. Electronic address: L.Dijkhuizen@rug.nl.
authors.forename: Lubbert
authors.initials: L
authors.lastname: Dijkhuizen
authors.affiliation: Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands; NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
authors.forename: Johannis P
authors.initials: JP
authors.lastname: Kamerling
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification; D002236:Carbohydrate Conformation; D002384:Catalysis; D045786:Diterpenes, Kaurane / Q000737:chemistry*; D005947:Glucose / Q000737:chemistry*; D006031:Glycosylation; D016695:Glycosyltransferases / Q000737:chemistry* / Q000302:isolation & purification; D052200:Limosilactobacillus reuteri / Q000737:chemistry* / Q000201:enzymology; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D036625:Stevia / Q000737:chemistry; D013395:Sucrose / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D045786:Diterpenes, Kaurane; C012042:steviol; D013395:Sucrose; C025474:rebaudioside A; D016695:Glycosyltransferases; C033837:alternansucrase; D005947:Glucose
keywords: Carbohydrate; Glycobiotechnology; NMR spectroscopy; Stevia rebaudiana; Steviol glycosides; Sweetener