Structure and conformation characterization of galactomannan from seeds of Cassia obtusifolia

author Lei Feng, Junyi Yin, Shaoping Nie, Yiqun Wan, Mingyong Xie
his workplace 1State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, Jiangxi, PR China2Center of Analysis and Testing, Nanchang University, Nanchang 330047, Jiangxi, PR China
periodicalFood Hydrocolloids, 2018, Vol.76 , pp.67-77
sourceElsevier Journal
DOI10.1016/j.foodhyd.2017.06.008
key word Cassia obtusifolia; Galactomannan; Structure; Conformation; NMR; Light scattering;
abstractAbstract(#br)The fine structure and conformational properties of neutral polysaccharide isolated from the whole seeds of Cassia obtusifolia (CP-30) were systematically investigated for the first time, by 1D and 2D NMR, size exclusion chromatography coupled with multiple detectors (SEC-MALS), dynamic light scattering (DLS), and static light scattering (SLS). The structure of CP-30 was elucidated to be a galactomannan, consisting of 1,4-linked-Man p backbone with side chains (T-Gal p ) attached to O -6 of 1,4-linked-Man p . DLS and SLS results showed that 0.6 M NaNO 3 was a good solvent for CP-30. The structure sensitive parameter ρ (1.33–1.80), the Mark-Houwink exponent α (0.59), and the conformational parameter ν (0.51 from z vs M w , and 0.52 from R h vs M w ) suggested a random coil conformation of CP-30 in solution. The molar mass per unit of contour length (356.6 nm ?1 ), persistent length (5.3 nm), and characteristic ratio (24.0) obtained by the wormlike cylinder model further indicated a dense random coil conformation of CP-30. By scanning electron microscopy, the linear chain shape of CP-30 in water was observed. The present research provided systematic information on structural and conformational properties of CP-30, which was important for elucidating the physicochemical characteristics of cassia polysaccharide and meaningful for its further application in food and medicinal industry.
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