A heparin-like glycosaminoglycan from shrimp containing high levels of 3-O-sulfated d-glucosamine groups in an unusual trisaccharide sequence

Abstract

The detailed characterization of a novel heparin-like glycosaminoglycan purified from the viscera (heads) of the shrimp Litopenaeus vannamei is reported. Structural analysis performed by mono- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy revealed it to be rich in both glucuronic acid and N,6-sulfated glucosamine residues. The key peculiarities were its high 3-O-sulfated glucosamine content compared to mammalian heparins; a residue which is usually associated with the antithrombin (AT) binding site, and the location of these residues within 2-O-sulfated iduronate and glucuronate-containing sequences (I2S–A∗–G), a situation not found in mammalian heparin. It also exhibited higher molecular weight (∼36kDa) than conventional heparin (∼16kDa) but, negligible anticoagulant activity (∼5IU/mg compared to heparin ∼190IU/mg) and stabilization of AT, which has been linked directly to anticoagulation activity. A high affinity fraction, eluting at a similar salt concentration (0.75–1.5M NaCl) from an antithrombin affinity column, to the high affinity fraction of heparin, also showed only weak thermal stabilization of AT (+∼2°C). These structural peculiarities may help elucidate more clearly the relationship between structure and function of sulfated polysaccharides, and provide useful model compounds with which to better understand interactions of biological significance.