Structural Characterization and Physicochemical Property of a Purified Fucosylated Glycosaminoglycan Sulfate From Holothuria leucospilota

A sulfated polysaccharide was purified from the body wall of the sea cucumber Holothuria leucospilota (HLP-Ⅰ). The structure of polysaccharides is critical for understanding and controlling their functional properties. Chemical and nuclear magnetic resonance (NMR) spectroscopic methods were applied for the primary structural characterization of this biopolymer. HLP-Ⅰ was a fucosylated glycosaminoglycan sulfate (FGs) with a weight-average molecular mass of 106.2 kDa. The main monosaccharide composition of HLP-Ⅰ is d-glucuronic acid (d-GlcA), n-acetylgalactosamine (n-GalNAc), and l-fucose (l-Fuc). And the sulfation patterns of the fucose branches were Fuc0S, Fuc3,4S, and Fuc2,4S at a ratio of 0.65:1.00:0.40. Moreover, HLP-Ⅰ was thoroughly characterized using high-performance size-exclusion chromatography (HPSEC), microscopy (SEM and AFM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). HLP-Ⅰ showed high amorphous platelets content and disordered arrangement, while the molecule adapted a sphere chain conformation in the 0.1 M NaNO₃ solution. Microscopy images showed that HLP-Ⅰ was a relatively smooth thin layer of hollow spherical particles. The gelation temperature was shown to be 211.6°C by DSC.