Sialoglycolipids structure

Later, from the eggs of S. intermedins, two sialoglycolipids were isolated that had the same type of structure as the sialoglycolipid from the gonads, but they contained only N-glycolylneuraminic acid, and, in one of them, this acid was sulfated.289,290... 

In the spermatozoa of the sea urchin Anthocidaris crassipina, nine sialoglycolipids were found, two of which were isolated and their structures established from the results of acid hydrolysis, methylation, and periodate oxidation.139 The major component of the glycolipid mixture is a disialo-glycolipid, NeuAc-(2- 8)-NeuAc-(2- 6)-Glc-Cer. The least-polar, minor component has the structure of a monosialoglycolipid, NeuAc-(2 - 6)-Glc-Cer. In these compounds, glucose is again the only neutral monosaccharide, and the sialic acid is attached to it at 0-6. 

From the S. nudus gonads, mono- and di-sialoglycolipids were isolated as well.291 Their structures are similar to those of the sialoglycolipids from A. crassipina. 

The second major sialoglycolipid from E. cordatum was the most acidic. Its carbohydrate chain contained one sialic acid residue and one glucosyl residue, as well as a sulfate group at C-8 of the sialic acid.141 This was the first example found in Nature of a sialoglycolipid containing a sulfated sialic acid. The structure proposed for the glycolipid is as follows. 

Thus, the sialoglycolipids from E. retifera and A. amurensis starfish, which are closely related, contain an amino sugar, absent from the sialoglycolipids of other species of echinoderm, and possess the same trisaccharide chain-structure for the asialo derivative. They differ, however, in the type of sialic acids, and their location in the carbohydrate chain. 

From the whole starfish were isolated three monosialoglycolipids whose carbohydrate chains contain glucose, galactose, arabinose, and N-glycolyl-neuraminic acid. From the results of partial hydrolysis with acid, methanoly-sis, methylation, and Cr03 oxidation, the following structures have been proposed for these sialoglycolipids. 

Therefore, from the starfish P. (A) pectinifera of the order of Spinulosa, unique sialoglycolipids not encountered in other species of animals have been isolated. At present, it is impossible to decide whether this type of structure is characteristic for the sialoglycolipids of starfish belonging to this order for such a decision to be made, it will be necessary to investigate further the other starfish species of Spinulosa. 

As in the case of the gangliosides in vertebrates, the sialoglycolipids in sea urchins are cell-surface antigens. A study of antigenic specificity for two disialoglycolipids (from the eggs of S. intermedius) whose structures differ in only one respect, that a sulfate group is present on the sialic acid... 

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