Revealing the Compact Structure of Lactic Acid Bacterial Heteroexopolysaccharides by SAXS and DLS

Research output: Contribution to journalJournal articleResearchpeer-review

Sanaullah Khan, Johnny Birch, Pernille Harris, Marie Rose Van Calsteren, Richard Ipsen, Günther H J Peters, Birte Svensson, Kristoffer Almdal

Molecular structures of exopolysaccharides are required to understand their functions and the relationships between the structure and physical and rheological properties. Small-angle X-ray scattering and dynamic light scattering were used in conjunction with molecular modeling to characterize solution structures of three lactic acid bacterial heteroexopolysaccharides (HePS-1, HePS-2, and HePS-3). Values of radius of gyration RG, cross-sectional radius of gyration RXS, approximate length L, and hydrodynamic diameter were not directly proportional to the molar mass and indicated the HePSs adopted a compact coil-like rather than an extended conformation. Constrained molecular modeling of 15000 randomized HePS-1 conformers resulted in five best-fit structures with R factor of 3.9-4.6% revealing random coil-like structure. φ and ψ angle analysis of glycosidic linkages in HePS-1 structures suggests Galf residues significantly influence the conformation. Ab initio scattering modeling of HePS-2 and HePS-3 gave excellent curve fittings with χ2 of 0.43 and 0.34 for best-fit models, respectively, compatible with coil-like conformation. The findings disclose solution behavior of HePS relevant for their interactions with biomacromolecules, for example, milk proteins.

Original languageEnglish
JournalBiomacromolecules
Volume18
Issue number3
Pages (from-to)747-756
Number of pages10
ISSN1525-7797
DOIs
Publication statusPublished - 2017

ID: 176654369