Periodate Oxidation of the Jelly Coat Substance of Echinocardium cordatum.

Abstract

In the jelly coat of the eggs of the sea-urchin a polysaccharide sulfate is combined with a protein. In E. cordatum, Strongylocentrotus droebachiensis, and Paracentrotus lividus the main carbohydrate component is polyfucose sulfate (Acta Chem. Scand. 2: 900. 1948; Arkiv Kemi 1: 39, 1949). Almost all of the S is present as easily hydrolyzable sulfate. During periodate oxidation half of the fucose residues are rapidly destroyed. Since in an unbranched chain only the terminal residues of fucose sulfate would have the unsubstituted alpha-glycol grouping required for reaction with periodate, the most probable structure is a branched polysaccharide chain. The structure of the polyfucose sulfate, fucoidin, from the brown seaweed, Fucus vesiculosus,is apparently quite dissimilar. A further possibility is that the protein and polysaccharide constituents do not exist as such in the molecule, but rather that the sugar and amino acid units are interlinked. The formation of denatured protein upon periodate oxidation confirms the hypothesis of a protein and a polysaccharide component in the jelly coat.