1997 Volume 9 Issue 48 Pages 315-330
The manyfold structural modifications of N-acetylneuraminic acid originating from the activities of various enzymes result in a large family of different sialic acids. Many of these sugars have been preserved in evolution since the echinoderms. Modifications, such as N-acetyl hydroxylation and O-acetylation, increase the structural diversity of sialoglycoconjugates and contribute to their variety of biological and pathophysiological roles. Out of a wealth of data a few examples of the functional highlights in sialobiology and sialopathology have been taken to illustrate our understanding and mirror the many unanswered questions, such as our incomplete knowledge about the distribution of the different sialic acids in microbial and animal species, as well as in developing, adult, ageing and malignantly transformed cells and tissues of animals and man. To fully understand the sialic acid modifications the enzymes involved in these processes have to be characterized and investigations of their regulation on the gene level are necessary.