Structural analysis of sulfated fucan from the sea cucumber Holothuria mexicana with the assistance of endo-1,3-fucanase.

Sulfated fucan from sea cucumber has received growing interest in recent decades. Insight into the primary structure of sulfated fucan is fundamental to elucidate their bioactivity. The sea cucumber Holothuria mexicana possesses a high market demand, while the structure of its sulfated fucan (Hm-FUC) remains unclear. This study investigates the structural characteristics of Hm-FUC, especially using a tool enzyme of heterologously expressed endo-1,3-fucanase (Fun168D). Hm-FUC demonstrated a 6.12 ± 0.45 % yield from the body wall of dried sea cucumber and a molecular weight of 475.2 ± 0.5 kDa. A set of procedures including enzymatic degradation, glycomics, and NMR analyses were introduced into the structural identification of Hm-FUC. The structure of Hm-FUC was determined to comprise a tetrafucose repeating unit [→3-α-l-Fucp2,4S-1 → 3-α-l-Fucp-1 → 3-α-l-Fucp2S-1 → 3-α-l-Fucp2S-1→]. The well-defined primary structure is beneficial for its application as nutritional component in foods and therapeutic agent in drugs.