Biological Significance of Sialic Acids

In the following Sections, the biological functions of sialic acids will be divided into four groups, and described on the basis of some well established examples selected from the flood of publications in 

As regards the function of this electronegative shield in some cell-types, membrane sialic acids prevent aggregation due to electrostatic repulsion in, for example, blood platelets, erythrocytes, and carcinoma cells in culture,418 whereas, in others, for example, chick, embryonic muscle-cells,422 aggregation is facilitated, most probably by Ca24 bridges. Sialic acid was also shown to be involved in the attachment both of endothelium and epithelium to glomerular basement-membranes of rat kidney.423 

The repulsive, electrostatic forces of sialic acids contribute to the rigidity of the cell surface, as was shown hy an increase in the defor-mability of sarcoma cells after enzymic removal of sialic acid residues.424 Enzymic release of sialic acids from the zona pellucida of rabbit ovum lessens the rigidity of this cell, and spermatozoa can no longer penetrate it.425 Glycoproteins on the surface of sea-urchin eggs 

Sialoglycoconjugates also seem to be involved in calcium binding of bone tissues.415 Neu as a component of an acidic glycoprotein is directly involved in the formation of a sperm reservoir in the vagina of the pig by salt-like coagulation with a basic protein of the boar ejaeu- 

The mucous secretions are vital, as they act as lubricants and defensive agents, in cavities of the body communicating with the environment, or on body surfaces.229 415 418 452 The influence of sialic acids on the macromolecular conformation seems to be the reason for the proteolytic resistance of several sialo-glycoproteins. The first example of such a role for sialic acids came from studies by Faillard and Pribilla453 that demonstrated a loss of the 

Werner Reutter, EckartKottgen, Christian Bauer, and WolfgangGerok  

Institut fur Molekularbiologie und Biochemie, Freie Universitat Berlin (Dahlem), 

Rosenberg and Schengrund 1976, Neufeld and Ashwell 1980, and Schauer 1982. The aim of this contribution, however, is to emphazise the important role of sialic acids in the occurrence of pathobiochemical alterations found in animals and human beings. 

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W. Reutier, E. Kottgen, C. Bauer, and W. Gerok, Biological significance of sialic acid, in Sialic Acids. Chemistry, Metabolism, and Function, R. Schauer, ed., Springer-Verlag, Vienna, 1982, p. 263. 

Reutter W, Kottgen E, Bauer C, Gerok W (1982) Biological significance of sialic acids. In Schauer R (ed) Sialic acids - Chemistry, metabolism and function. Springer, Berlin Heidelberg New York, p 263... 

Examples of the Clinical and Biological Significance of Sialic Acid Diversity. 135... 

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