Mucins oligosaccharide chains

Besides the prominent mucin domains, gel-forming mucins have other domains (i.e., CS-, D-, C-, and CK-domains as shown in Fig. 2.1) (Perez-Vilar and Hill 1999 Dekker et al. 2002) characterized by being (a) under-glycosylated, although most have one or more N-linked oligosaccharide chains (see Section... 

Xia J, Alderfer JL, cf. Piskorz, Matta KL, Total synthesis of sialylated and sulfated oligosaccharide chains from respiratory mucins, Chemistry, 6(18) 3442-51, 2000. 

Purified human asthmatic bronchial mucin has a minimum molecular weight of 1.8 X10 with aggregates of 1 X 10 or greater.Oligosaccharide chains are linked iV-glycosidically via 2-acetamido-2-deoxy-D-galactosyl residues to L-serine or L-threonine residues, which account for approximately one of every five amino-acids in the protein. 

Neisseria meningitidis is a pathogen that causes meningitis in humans. It has an unusual capsular homopolysaccharide that is composed of A -acetyl-D-neuraminic acid. The monosaccharide residue has nine carbons (see Fig. 6.20A). It makes up a family of sugar acids called sialic acids that are N- and 0-substituted derivatives (see Chapter 9). The sialic acids are widely distributed and are primarily found at the ends of the oligosaccharide chains attached to glycoproteins that are especially prevalent in bovine and ovine submaxillary mucins, erythrocytes, and nerve tissues. A -acetyl-D-neuraminic acid is biosynthesized by an aldol condensation of pyruvic acid with N-acetyl-D-mannosamine (see Chapter 10). 

Based on the structure of hog submaxillary mucin oligosaccharide side chains proposed by Baig and Aminoff (1972), another sialyltransfer-ase, responsible for the addition of sialic acid linked to j8-galactosyl residues, remains to be isolated from hog submaxillary tissues (see Figure 11). 

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