Isolation and characterization of a novel chondroitin sulfate from squid liver integument rich in N-acetylgalactosamine(4 ,6 -disulfate) and glucuronate(3 -sulfate) residues

Unique disaccharide composition of novel chondroitin sulfate from squid liver integument rich in N-acetylgalactosamine(4,6-disulfate) and glucuronate(3-sulfate) residues. 2S, 3S, 4S, and 6S represent 2-sulfate, 3-sulfate, 4-sulfate and 6-sulfate, respectively. Novel chondroitin sulfate (CS) chains with an average molecular mass of 79.6 kDa were purified from squid liver integument. A compositional analysis of the CS chains using chondroitinases (CSases) ABC and AC-I revealed a range of variably sulfated disaccharides with GlcAβ1→3GalNAc(6-sulfate), GlcAβ1→3GalNAc(4-sulfate), and GlcAβ1→3GalNAc(4,6-disulfate) as the major ones, significant amounts of rare 3-sulfated GlcA-containing disaccharides, and a small amount of nonsulfated GlcAβ1→3GalNAc. The CS chains exhibited neurite outgrowth-promoting activity toward embryonic mouse hippocampal neurons, which was abolished completely by digestion with CSase ABC or AC-I. Consequently, whether these CS chains interact with heparin-binding growth factors was tested in a BIAcore system. All of the growth factors exhibited concentration-dependent and specific binding. CS chains from squid liver integument, with their unique composition and strong biological activities, may be a good candidate for therapeutic application.