title: Revealing the Compact Structure of Lactic Acid Bacterial Heteroexopolysaccharides by SAXS and DLS.
abstract: 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 χ2of 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.
authors.affiliation: Department of Micro- and Nanotechnology, DTU , Ørsteds Plads, Building 423, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Sanaullah
authors.identifier: 0000-0003-2480-6239
authors.initials: S
authors.lastname: Khan
authors.affiliation: Enzyme and Protein Chemistry, Department of Systems Biology, DTU , Elektrovej, Building 375, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Johnny
authors.initials: J
authors.lastname: Birch
authors.affiliation: Department of Chemistry, DTU , Kemitorvet, Building 207, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Pernille
authors.initials: P
authors.lastname: Harris
authors.affiliation: Saint-Hyacinthe Research and Development Centre, Agriculture and Agri-Food Canada , 3600 Casavant Boulevard West, Saint-Hyacinthe, Quebec J2S 8E3, Canada.
authors.forename: Marie-Rose
authors.initials: MR
authors.lastname: Van Calsteren
authors.affiliation: Department of Food Science, University of Copenhagen , Rolighedsvej 26, DK-1958 Frederiksberg, Denmark.
authors.forename: Richard
authors.initials: R
authors.lastname: Ipsen
authors.affiliation: Department of Chemistry, DTU , Kemitorvet, Building 207, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Günther H J
authors.initials: GH
authors.lastname: Peters
authors.affiliation: Enzyme and Protein Chemistry, Department of Systems Biology, DTU , Elektrovej, Building 375, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Birte
authors.initials: B
authors.lastname: Svensson
authors.affiliation: Department of Micro- and Nanotechnology, DTU , Ørsteds Plads, Building 423, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Kristoffer
authors.identifier: 0000-0002-5490-9303
authors.initials: K
authors.lastname: Almdal
mesh_terms: D000067493:Dynamic Light Scattering; D057446:Hydrodynamics; D007777:Lactobacillaceae / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D008970:Molecular Weight; D011134:Polysaccharides / Q000737:chemistry*; D053838:Scattering, Small Angle; D012996:Solutions
chemical_list: D011134:Polysaccharides; D012996:Solutions