Chain conformational and physicochemical properties of fucoidans from sea cucumber

• Fucoidans from sea cucumber (SC-FUCs) were prepared and investigated.
• Chain conformation was analyzed by HPSEC-MALLS-Visc-RI and worm-like cylinder model.
• SC-FUCs adopted random coil conformation in 150 mM NaCl solution.
• Branch structure but sulfated pattern greatly influence chain flexibility.
• Rheological, electrical and thermal properties were also clarified.

Although fucoidans from sea cucumber (SC-FUCs) have been proven as potential bioactive polysaccharides and functional food ingridents, their chain conformation and physicochemical properties were still poorly understood. This study investigated the chain conformation of fucoidans from sea cucumber Acaudina molpadioides (Am-FUC), Isostichopus badionotus (Ib-FUC) and Apostichopus japonicus (Aj-FUC), of which primary structure has been recently clarified. Chain conformation parameters demonstrated that studied SC-FUCs adopted random coil conformation in 150 mM NaCl solution (pH 7.4). Based on the worm-like cylinder model and atomic force microscopy, the chain stiffness of SC-FUCs was further evaluated as Am-FUC ≈ Ib-FUC > Aj-FUC. It was suggested that the existence of branch structure increased the chain flexibility, while sulfated pattern exerted limited influence. SC-FUCs demonstrated shear-thinning rheological behavior and negative charge. Am-FUC possessed a higher thermostability than Ib-FUC and Aj-FUC. These results have important implications for understanding the molecular characteristics of SC-FUCs, which could facilitate their further application.