Title
Structural characterization of bioengineered α-D-glucans produced by mutant glucansucrase GTF180 enzymes of lactobacillus reuteri strain 180
Author
van Leeuwen, S.S.
Kralj, S.
Eeuwema, W.
Gerwig, G.J.
Dijkhuizen, L.
Kamerling, J.P.
Publication year
2009
Abstract
Mutagenesis of specific amino acid residues of the glucansucrase (GTF180) enzyme from Lactobacillus reuteri strain 180 yielded 12 mutant enzymes that produced modified exopolysaccharides (mEPSs) from sucrose. Ethanol-precipitated and purified mEPSs were subjected to linkage analysis, Smith degradation analysis, and 1D/2D 1H NMR spectroscopy. Comparison of the results with structural data of the previously described wild type EPS180 and triple mutant mEPS-PNNS revealed a broad variation of structural elements between mEPS molecules. The amount of (α1→3) linkages varied from 14-43%, the amount of (α1→4) linkages (not present in the wild type) from 0-12%, and the amount of (α1→6) linkages from 51-86%. The average molecular weight (Mw) ranged from 9.4 to 32.3 MDa and the degree of branching varied from 8-20%. Using a previously established 1H NMR structural-reporter-group concept, composite models, that include all identified structural features, were formulated for all mEPS molecules. Variations in the mEPS structures strongly affected the physical properties of the mEPSs. © 2009 American Chemical Society.
Subject
Biology
Amino acid residues
Average molecular weights
Composite models
Degree of branching
Exopolysaccharides
Glucans
Glucansucrase
H nmr spectroscopies
Lactobacillus reuteri
Linkage analysis
Mutant enzymes
Smith degradations
Structural characterizations
Structural datum
Structural elements
Structural features
Triple mutants
Wild types
Amines
Amino acids
Catalysts
Chains
Ethanol
Nuclear magnetic resonance
Nuclear magnetic resonance spectroscopy
Organic acids
Polysaccharides
Sugar (sucrose)
Enzymes
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DOI
https://doi.org/10.1021/bm801240r
TNO identifier
279997
ISSN
1525-7797
Source
Biomacromolecules, 10 (3), 580-588
Document type
article