Sialic acid-binding lectins

MAG (Siglec-4a) is a member of the siglec family of sialic acid (NeuSAc) binding I-type lectins (carbohydrate binding proteins) within the immunoglobulin superfamily IgSF (Table 16.1) [16]. 

From the literature, little is known about specific interactions in bacterial adhesion to polymers. In the adhesion of S. sanquis to saliva-coated hydroxyl apatite (HA), the existence of two specific receptor sites on HA could be demonstrated to which sialic acid lectins can bind. Vaudaux, et al., found in adhesion experiments of S. aureus to fibronectin-coated PMMA coverslips, that presumably a specific site in the amino-terminal region of fibronectin is involved in the adhesion process, and that collagen may play a role as an adhesion cofactor. 

D. Zanini and R. Roy, Synthesis of new a-thiosialodendrimers and their binding properties to the sialic acid specific lectin from Limaxflavus, J. Am. Chem. Soc., 119 (1997) 2088-2095. 

Incomplete (N-linked) glycosylation prompts decreased in vivo activity due to more rapid hepatic clearance of the EPO molecule. Enzymatic removal of terminal sialic acid sugar residues from oligosaccharides exposes otherwise hidden galactose residues. These residues are then free to bind specific hepatic lectins, which promote EPO removal from the plasma. The reported plasma tm value for native EPO is 4-6 h. The tm for desialated EPO is 2 min. Comparison of native human EPO with its recombinant form produced in CHO cells reveals very similar glycosylation patterns. 

Polythiophenes functionalized with monosaccharides have been evaluated for their ability to detect the influenza virus and E. coli (Baek et al. 2000). Copolymers of thiophene acetic acid 10 and carbohydrate-modified thiophenes 11 have been prepared via iron(III) chloride mediated polymerization. Addition of influenza virus to a sialic acid containing copolymer resulted in a blue shift of the polymer absorption maximum, resulting in an orange to red chromatic transition. Mannose-containing polythiophenes underwent color changes upon the addition of the lectin ConA or E. coli cells that contain cell surface mannose-binding receptors. A similar biotinylated pol5hhiophene afforded a streptavidin responsive material (Paid and Leclerc 1996). 

Ratanapo S, Ngamjunyaporn W, Chulavatnatol M. Sialic acid binding lectins from leaf of mulberry (Moms alba). Plant Science 1998 139 141-148. 

The Indian horse-shoe crab Carcinoscorpius rotunda caudu also contains a sialic acid-binding lectin (carcinoscorpin), which was purified almost to homogeneity, and had205 a molecular weight of 420,000. 

An important role of cell-surface sialic acids in the regulation of normal cellular-interaction may be assumed, because lectins are widespread in tissues that recognize /3-D-galactosyl residues, and thus may participate in cell adhesion.522-524 It is conceivable that variations in the sialylation of cell-surface, D-galactosyl residues modulate the strength of cellular binding. 

Cholera toxin consists of one 240-residue A subunit and a ring of five 103-residue B subunits.c e The latter is a "targeting complex," a bacterial lectin each subunit of which binds to the galactose and sialic acid termini of a single molecule of ganglioside Gm1. 

When the incubations were performed in the presence of WGA (sufficient lectin was added to provide at least one equivalent of binding sites, based on the amount of sialic acid formed in the control experiments) the product distribution was observed to change dramatically over time (Figure... 

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