title: Optimization of reaction conditions by RSM and structure characterization of sulfated locust bean gum.
abstract: Sulfated derivatives of galactomannan from locust bean gum (LBG) with the degree of substitution (DS) of 0.34-1.07 were synthesized using chlorosulfonic acid/pyridine (CSA/Py) method. Box-Behnken design (BBD) of response surface methodology (RSM) was employed to optimize the reaction conditions. Results of FT-IR and X-ray photoelectron spectroscopy (XPS) indicated that SO3H groups were widely present in sulfated LBG (SLBG). (13)C NMR result revealed that sulfation had occurred and C-6 substitution was predominant in SLBG. All sulfated samples showed a decrease in Mw and more broad molar mass distribution in size exclusion chromatography combined with laser light scattering (SEC-LLS) analysis. Results of MW - [Formula: see text] showed a decrease in fractal dimension (df) value. Laser light scattering results also showed a conformation transition from a compact chain conformation of branched clusters to a random coil conformation of SLBG. Compared to LBG and SLBG with low DS and molecular weight, SLBG2 exhibited an internal structure of random coil with a DS of 1.07. DS and molecular weight had great influence on its conformation in aqueous solution. Our results confirmed that the degradation of polysaccharide and SO3H groups improved significantly the stiffness of the chains due to the electrostatic effect.
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, People's Republic of China; Bioactive Products Engineering Research Center For Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, People's Republic of China. Electronic address: nuno-vai@163.com.
authors.forename: Junlong
authors.initials: J
authors.lastname: Wang
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, People's Republic of China; Bioactive Products Engineering Research Center For Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, People's Republic of China.
authors.forename: Ting
authors.initials: T
authors.lastname: Yang
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, People's Republic of China; Bioactive Products Engineering Research Center For Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, People's Republic of China.
authors.forename: Jia
authors.initials: J
authors.lastname: Tian
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, People's Republic of China; Bioactive Products Engineering Research Center For Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, People's Republic of China.
authors.forename: Wenxi
authors.initials: W
authors.lastname: Liu
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, People's Republic of China; Bioactive Products Engineering Research Center For Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, People's Republic of China.
authors.forename: Fan
authors.initials: F
authors.lastname: Jing
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, People's Republic of China; Bioactive Products Engineering Research Center For Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, People's Republic of China.
authors.forename: Jian
authors.initials: J
authors.lastname: Yao
authors.affiliation: College of Life Science, Northwest Normal University, Lanzhou 730070, People's Republic of China; Bioactive Products Engineering Research Center For Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, People's Republic of China; Key Laboratory of Eco-Environment-Related Polymer Materials Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, People's Republic of China.
authors.forename: Ji
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Eco-Environment-Related Polymer Materials Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, People's Republic of China.
authors.forename: Ziqiang
authors.initials: Z
authors.lastname: Lei
keywords: Galactomannan; Locust bean gum; Response surface methodology; Solution conformation; Sulfation