title: Heat-induced conformation transition of the comb-branched β-glucan in dimethyl sulfoxide/water mixture.
abstract: We studied the chain conformation transition of the comb-branched β-glucan (AF1) isolated from Auricularia auricula-judae by heating associated with dimethyl sulfoxide (DMSO). The results from1H NMR and differential scanning calorimeter (DSC) indicated that the reversible hydrogen bonds between side chains of AF1 and water clusters formed at relatively low temperatures. With increasing vDMSOto 0.70, the transition temperature (Tm) increased from 9 to 71°C, and then decreased to 57°C with continuously increasing vDMSOdue to the competition between DMSO and water for forming hydrogen bonds. Additionally, the combined analysis of13C NMR, viscosity and light scattering revealed an obvious stiff-to-flexible chain conformation transition of AF1, which occurred at 95-130°C, 120-145°C and 130-160°C with vDMSOof 0.90, 0.85 and 0.70, respectively. This work demonstrated that AF1 has complex structure under different conditions, and the results obtained herein would benefit us to understand its specific behaviors including hollow fibril and anti-hepatoma activity.
authors.affiliation: School of Pharmaceutical Science, Jiangnan University, Wuxi 214122, China; College of Chemistry & Molecule Sciences, Wuhan University, Wuhan 430072, China.
authors.forename: Shuqin
authors.initials: S
authors.lastname: Xu
authors.affiliation: College of Chemistry & Molecule Sciences, Wuhan University, Wuhan 430072, China.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Xu
authors.affiliation: School of Physics and Materials Science & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China.
authors.forename: Min
authors.initials: M
authors.lastname: Xu
authors.affiliation: Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599, USA.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: O'Leary
authors.affiliation: College of Chemistry & Molecule Sciences, Wuhan University, Wuhan 430072, China. Electronic address: zhangln@whu.edu.cn.
authors.forename: Lina
authors.initials: L
authors.lastname: Zhang
mesh_terms: D001487:Basidiomycota / Q000737:chemistry*; D004121:Dimethyl Sulfoxide; D006358:Hot Temperature; D008968:Molecular Conformation; D014867:Water; D047071:beta-Glucans / Q000737:chemistry*
chemical_list: D047071:beta-Glucans; D014867:Water; D004121:Dimethyl Sulfoxide
keywords: Conformation transition; Differential scanning calorimeter; Hydrogen bonds; Light scattering; Stiff chain; β-Glucan