Abstract
Shark fin, used as a food, is a rich source of glycosaminoglyans (GAGs), acidic polysaccharides having important biological activities, suggesting their nutraceutical and pharmaceutical application. A comprehensive survey of GAGs derived from the fin was performed on 11 elasmobranchs, including several deep sea sharks. Chondroitin sulfate (CS) and hyaluronic acid (HA) were found in Isurus oxyrinchus, Prionace glauca, Scyliorhinus torazame, Deania calcea, Chlamydoselachus anguineus, Mitsukurina owatoni, Mustelus griseus and Dasyatis akajei, respectively. CS was only found from Chimaera phantasma, Dalatias licha, and Odontaspis ferox, respectively. Characteristic disaccharide units of most of the CS were comprised of C- and D-type units. Interestingly, substantial amount of CS/dermatan sulfate (DS) was found in the dried fin (without skin and cartilage) of Isurus oxyrinchus and Prionace glauca. 1H-NMR analysis showed that the composition of glucuronic acid (GlcA) and iduronic acid (IdoA) in shark CS/DS was 41.2% and 58.8% (Isurus oxyrinchus), 36.1% and 63.9% (Prionace glauca), respectively. Furthermore, a substantial proportion of this CS/DS consisted of E-, B- and D-type units. Shark CS/DS stimulated neurite outgrowth of hippocampal neurons at a similar level as DS derived from invertebrate species. Midkine and pleiotrophin interact strongly with CS/DS from Isurus oxyrinchus and Prionace glauca, affording Kd values of 1.07 nM, 6.25 nM and 1.70 nM, 1.88 nM, respectively. These results strongly suggest that the IdoA-rich domain of CS/DS is required for neurite outgrowth activity. A detailed examination of oligosaccharide residues, produced by chondroitinase ACII digestion, suggested that the IdoA and B-type units as well as A- and C-type units were found in clusters in shark CS/DS. In addition, it was discovered that the contents of B-type units in these IdoA-rich domain increased in a length dependent manner, while C- and D-type units were located particularly in the immediate vicinity of the IdoA-rich domain.
Highlights
Glycosaminoglycans (GAGs) are a group of structurally related polysaccharides, found as the carbohydrate moieties of proteoglycans (PGs) or as free chains in the case of hyaluronic acid (HA)
GAGs including one or two bands corresponding to the migration positions of HA or chondroitin sulfate (CS) standards disappeared on ChaseABC or ChaseACII digestion
Available CS is usually prepared from shortfin mako shark and blue shark cartilage
Summary
Glycosaminoglycans (GAGs) are a group of structurally related polysaccharides, found as the carbohydrate moieties of proteoglycans (PGs) or as free chains in the case of hyaluronic acid (HA). The GAG components of PGs are linear, sulfated polysaccharides containing hexosamine and uronic acid (or galactose (Gal)) disaccharide repeating sequence and include chondroitin sulfate (CS), dermatan sulfate (DS), heparin (HP), heparan sulfate (HS), keratan sulfate (KS) [1]. The repeating disaccharides of CS and DS can be sulfated at the C-2 position of GlcA or IdoA and at the C-4 and/or C-6 positions of GalNAc in animals [2,3,4,5,6]. The disaccharide units in CS and DS are classified into five groups, GlcA/IdoA-GalNAc (4S) (A-type unit), GlcA/IdoA-GalNAc (6S) (C-type unit), GlcA/IdoA (2S)-GalNAc (4S) (B-type unit), GlcA/ IdoA (2S)-GalNAc(6S) (D-type unit) and GlcA/IdoA-GalNAc (4S, 6S) (E-type unit) and the physiological function of CS and DS, such as differentiation, migration, tissue morphogenesis, immune response, blood clotting and wound repair, depend on the binding between their sulfated oligosaccharides and the functional proteins in mammals [5,7,8,9]
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