Structure, enzymatic transformation, anticancer activity of fucoidan and sulphated fucooligosaccharides from Sargassum horneri

Structure and anticancer activity of fucoidan from Sargassum horneri and from products of its enzymatic transformation were investigated. A gene that encodes fucoidanase ffa1 in the marine bacteria F. algae was identified, cloned and the protein (FFA1) was produced in Escherichia coli. The mass of the gene product FFA1 is 111 kDa. Sequence analysis has revealed that fucoidanase FFA1 belongs to the GH107 (CAZy) family. Recombinant fucoidanase FFA1 was used to produce fucooligosaccharides. Structure of 5 sulphated oligosaccharides with polymerization degree 4-10 was established by NMR-spectroscopy. The fucoidan extracted from S. horneri is almost pure fucan. The main chain of the fucoidan is established to consist mostly of the repeating →3-α-l-Fucp(2SO3−)-1 → 4-α-l-Fucp(2,3SO3−)-1→ fragment, with insertions of →3-α-l-Fucp(2,4SO3−)-1→ fragment. Unsulphated side chains with the α-l-Fucp-1 → 2-α-l-Fucp-1→ structure connect to the main one at the C4 of monosaccharide residue.