Glycoproteins sialic acid

This fraction contained carbohydrates typical of membrane glycoproteins and was especially rich in galactose and sialic acid. Glycoproteins in this fraction avidly bound the lectin Concanavalin A. 

Schauer R, Kamerling JP (2003) In Montreuil J, Vliegenthart JFG, Schachter H (eds) Chemistry, biochemistry and biology of sialic acid, glycoproteins II. Elsevier, Amsterdam, pp 243-402... 

Bosmann, H. B., 1972, Platelet adhesiveness and aggregation. II. Surface sialic acid, glycoprotein iV-acetylneuraminic acid transferase, and neuraminidase of human blood platelets, Biochim. Biophys. Acta 279 456. 

Factor V. High in sialic acid content. Factor V is a large asymmetric single-chain glycoprotein that becomes an active participant in the coagulation cascade when it is converted to its active form by a-thrombin. Approximately 25% of human Factor V is found in the whole blood associated with platelets. Factor V is an essential cofactor along with Factor Xa plus phosphohpid plus Ca " in the conversion of prothrombin to thrombin. 

Corfleld AP, Schauer R (1982) Metabolism of sialic acids. In Schauer R (ed) Sialic acids - Chemistry, metabolism and function. Springer, Wien, pp 195-261 Corfleld AP, Higa H, Paulson JC, Schauer R (1983) The specificity of viral and bacterial sial-idases for alpha(2-3)- and alpha(2-6)-linked sialic acids in glycoproteins. Biochim Biophys Acta 744 121-126... 

Varghese IN, Colman PM (1991) Three-dimensional structure of the neuraminidase of influenza virus A/Tokyo/3/67 at 2.2 A resolution. 1 Mol Biol 221 473 86 Varghese IN, Laver WG, Colman PM (1983) Structure of the influenza virus glycoprotein antigen neuraminidase at 2.9 A resolution. Nature 303 35 0 Varghese IN, McKimm-Breschkin IL, Caldwell IB, Kortt AA, Colman PM (1992) The structure of the complex between influenza virus neuraminidase and sialic acid, the viral receptor. Proteins 14 327-332... 

N-Acetylneur-aminic acid Sialic acid (nine C atoms) NeuAc CMP-NeuAc Often the terminal sugar in both N- and 0-linked glycoproteins. Other types of sialic acid are also found, but NeuAc is the major species found in humans. Acetyl groups may also occur as 0-acetyl species as well as N-acetyl. 

Figure 1.29 Monosaccharides containing carboxylate groups. Sialic acid often is found at the terminal residues of polysaccharides within glycoproteins.

Since sialic acid is a frequent terminal sugar constituent of the polysaccharide trees on glycoproteins, this method selectively forms reactive aldehydes on the most accessible parts for subsequent modifications. The carbohydrate polymer of a protein provides a long spacer arm that can be used to conjugate another large macromolecule, such as a second protein, with little steric problems. 

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