Structural Elucidation of the Component Trisaccharide Obtained from the Acrosome Reaction-Inducing Substance of the StarfishAsterias Amurensisby Chemical Synthesis

Abstract

Abstract Okinaga et al.1 have recently reported a novel trisaccharide obtained from the acrosome reaction-inducing substance (ARIS) of the starfish Asterias amurensis. The ARIS is essential for triggering the acrosome reaction in homologous spermatozoa, and the biological activity is due to the sugar moiety. The trisaccharide, composed of xylose (Xyl), galactose (Gal), and fucose (Fuc), and proposed to have a sequence of Xyll→3Gall→3 or 4[4 or 3-(So3 −)]Fuc, was deduced to be one of the major structural units constructing the side chain of the high molecular carbohydrate portion of the ARIS. The sequence differs from similar oligosaccharides, found in hemicellulose2 and composed of d-xylose, d-galactose, and l-fucose. The ARIS contains a unique saccharide chain having sulfated l-fucose as an internal residue. This unique structure prompted us to synthesize the trisaccharide as well as to reveal the anomeric configuration of Xyl and Gal moieties and the sulfated position of Fuc residue.