Identification of the sialic acids from the egg jelly coat of the sea urchin Pseudocentrotus depressus (Okayama).

The jelly coat substance of the sea urchin eggs of Pseudocentrotus depressus (Okayama) was found to contain 0.35% sialic acids. After isolation of the sialic acids from the purified sulfated sialoglycoprotein containing 11% of sialic acids, analysis by colorimetry, thin-layer chromatography and gas-liquid chromatography/mass spectrometry demonstrated the nature of the sialic acids to be N-glycolylneuraminic acid and 9-O-acetyl-N-glycoloylneuraminic acid. The molar ratio between both sialic acids was found to be 1 : 1. Since it is known that O-acyl groups are partially released during the hydrolysis and isolation procedure, it can be assumed that in the native glycoprotein the percentage of O-acetylation is much higher than 50%. The sugar and sulfate composition of the glycoprotein is also described.