Structure of the Main Saccharide Chain in the Acrosome Reaction-inducing Substance of the Starfish, Asterias amurensis

The structure of the main saccharide chain of the acrosome reaction-inducing substance in the egg jelly coat of the starfish, Asterias amurensis , is composed of the following pentasaccharide repeating units (Structure I). A polymer consisting of 10–11 repeating units has been observed to induce the acrosome reaction in starfish sperm at high calcium concentrations. → 4 \) ­ β ­ D ­ Xyl p ­ \( 1 → 3 \) ­ α ­ D ­ Gal p ­ \( 1 → 3 \) ­ α ­ L ­ Fuc p ­ \( 1 → 3 \) ­ α ­ L ­ Fuc p ­ \( 1 → 4 \) ­ α ­ L ­ Fuc p ­ \( 1 → 4 ↑ ↑ SO 3 − SO 3 − Structure I The identities and linkage positions of constituent sugars were established using sugar, methylation, and sulfate analyses together with one- and two-dimensional nmr spectroscopy. The structure was supported by the data obtained for desulfation products and the Smith degradation of the polysaccharide.