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Sialylation and desialylation

Sialic acids (Sias) are a family of 9-carbon containing acidic monosaccharides that often present at the terminal of glycan structures of glycoproteins and glycolipids [1]. Actually, Sias are attached to either galactose (Gal), N-acetyl galactosamine (GalNAc) unit via α2,3- or α2,6-linkage, or Sias via α2,8(9)-linkage, known as sialoform [2]. Sias are involved in various biological processes through (i) their hydrophilic and negative charge exerting physicochemical effects on the glycoconjugates to which they are attached, (ii) serving as recognition sites, or (iii) masking recognition sites of the glycoconjugates [1-4]. The levels and linkages of Sias, known as sialylation status is a fine balance between sialylation (attachment of Sias) and desialylation (removal of Sias), which is maintained by sialyltransferases and sialidases, respectively [3,4]. Desialylation, leading to modulating the functionality of the Sia-containing molecules, is often involved in signal transduction of either physiological or pathological processes [5].


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Figure. 1. Sialic acids (Sias) and their linkages, sialylation and desialylation.