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Published on: October 25, 2017
Temperature- and sodium-hydroxide-dependent regulation of single-helix curdlan conformations
Xiaoshuang Yan1, Geying Ru2, Jiwen Feng2
1Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Synthetic Biology Infrastructure, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China; State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430071, China.
Abstract:
Curdlan exhibits diverse biological activities. However, elucidating the structure-activity relationship of curdlan remains challenging owing to its conformational complexity and variability in well-defined systems. This study systematically examines the impact of temperature, sodium hydroxide (NaOH) concentration, and curdlan concentration on the single-helix conformation of curdlan. 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, small-angle X-ray scattering, gel permeation chromatography, and dynamic light scattering analyses confirm that the single-helix conformation of curdlan is successfully formed in dilute (0.15 M-0.24 M) NaOH solutions within the temperature range of 35 °C-50 °C, whereas partial conversion to aggregated or mixed helical structures occurs at lower temperatures (5 °C-25 °C). 23Na NMR parameter variations reveal direct Na+ interactions with the random-coil or single-helix conformations of curdlan. NMR and ultraviolet-visible absorption spectroscopy experiments confirm that the single-helix structure of curdlan facilitates stable encapsulation of Congo red via supramolecular assembly at 35 °C-50 °C. This study provides new insights into the conformation-activity relationships of β-(1,3)-glucans.
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