The type of naturally occurring sialic acids

Abstract

The results obtained in this laboratory and others about the type of sialic acids contained in materials from the animal kingdom (mammals, birds,- fishes and echino­ derms), alga and bacteria, are summarized and distributed according to their source.

It may be deduced that sialic acids are widely distributed in Nature. The same sialic acid can be found in very different species, although not at the same concentration.

In contrast, in very close species (from a taxonomic point of view) the type and concentration of their sialic acids may be different for the same material (generally, serum).

Our results with some vegetal materials (kidney beans, pea seeds, lentils, sweet almonds, orange seeds and peels, and green peppers) giving a positive thiobarbituric acid reaction and identical color in some cases to that obtained with the acylneuraminic acids, do not permit to admit the occurrence of sialic acids in these materials.

It is not possible to find a correlation between the occurrence and concentration of N-glycolylneuraminic acid and acetylneuraminic acids in different taxonomic groups of the most evolved beings.