title: SANS measurements of semiflexible xyloglucan polysaccharide chains in water reveal their self-avoiding statistics.
abstract: We explored the behavior and the characteristics of xyloglucan polysaccharide chains extracted from tamarind seeds in aqueous media. The initial solubilization is achieved by using a 0.01 M NaOH solution. The absence of compact aggregates in the solution and the average molecular mass of the individual chains were unambiguously demonstrated by size exclusion chromatography with multi-angle light scattering detection. The composition and the stability of the solution were quantitatively checked over weeks by using liquid state nuclear magnetic resonance with DMSO as internal standard. The conformational characteristics of the chains were measured using nondestructive small-angle neutron scattering (SANS). The unambiguous determination of the Flory exponent (ν = 0.588) by SANS enabled us to directly prove that xyloglucan chains in water behave like semiflexible worm-like chains with excluded volume statistics (good solvent), contrary to most of the neutral water-soluble polymer chains that rather exhibit Gaussian statistics (θ-solvent). In addition to the Flory exponent, the persistence length l(p) and the cross section of the chains were also determined by SANS with utmost precision, with values of 80 and of 7 Å, respectively, which provides a complete description of the conformational characteristics of XG chains at all relevant length scales.
authors.affiliation: Laboratoire Léon Brillouin, CEA Saclay, 91191 Gif sur Yvette Cedex, France.
authors.forename: François
authors.initials: F
authors.lastname: Muller
authors.forename: Sabine
authors.initials: S
authors.lastname: Manet
authors.forename: Bruno
authors.initials: B
authors.lastname: Jean
authors.forename: Gérard
authors.initials: G
authors.lastname: Chambat
authors.forename: François
authors.initials: F
authors.lastname: Boué
authors.forename: Laurent
authors.initials: L
authors.lastname: Heux
authors.forename: Fabrice
authors.initials: F
authors.lastname: Cousin
mesh_terms: D001709:Biotechnology / Q000379:methods*; D002236:Carbohydrate Conformation; D002850:Chromatography, Gel; D005936:Glucans / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D018583:Pliability; D011134:Polysaccharides / Q000737:chemistry*; D053838:Scattering, Small Angle; D012639:Seeds / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry; D012996:Solutions; D029861:Tamarindus / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014990:Xylans / Q000737:chemistry*
chemical_list: D005936:Glucans; D011134:Polysaccharides; D012996:Solutions; D014990:Xylans; D014867:Water; C029353:xyloglucan; D012972:Sodium Hydroxide