Submaxillary mucin

Figure 47-2. Structures of two 0-linked oligosaccharides found in (A) submaxillary mucins and (B) fe-tuin and in the sialoglycoprotein of the membrane of human red blood cells. (Modified and reproduced, with permission, from LennarzWJ The Biochemistry of Glycoproteins and Proteoglycans. Plenum Press, 1980.)...

Savage, A.V., Donohue, J.J., Koeleman, C.A.M. and van den Eijnden, D.H. (1990) Structural characterization of sialylated tetrasaccharides and pentasaccharides with blood-group H and Lex activity isolated from bovine submaxillary mucin. European Journal of Biochemistry 193, 837-843. 

The mucin of the submaxillary gland appears to contain two muco-proteins.170 One js a D-glucosamine-di-n-mannose complex similar to that in the serum proteins, while the other is claimed to be a crystalline substance ChH260iiN, containing D-glucosamine, two acetyl residues and a polyhydroxy acid which is not a uronic acid. It appears to be a type of sulfate-free chondroitin. 

T. K. Dam, T. A. Gerken, B. S. Cavada, K. S. Nascimento, T. R. Moura, and C. F. Brewer, Binding studies of a-GalNAc specific lectins to the a-GalNAc (Tn-antigen) form of porcine submaxillary mucin and its smaller fragments, J. Biol. Chem., 282 (2007) 28256-28263. 

A. E. Eckhardt, C. S. Timpte, A. W. DeLuca, and R. L. Hill, The complete cDNA sequence and structural polymorphism of the polypeptide chain of porcine submaxillary mucin, J. Biol. Chem., 272 (1997) 33204—33210. 

D. Carlson, Structures and immunological properties of oligosaccharides isolated from pig submaxillary mucins, J. Biol. Chem., 243 (1968) 616-626. 

T. A. Gerken and N. Jentoft, Structure and dynamics of porcine submaxillary mucin as determined by natural abundance carbon-13 NMR spectroscopy, Biochemistry, 26 (1987) 4689-4699. 

T. A. Gerken, C. L. Owens, and M. Pasumarthy, Determination of the site-specific O-glycosylation pattern of the porcine submaxillary mucin tandem repeat glycopeptide, J. Biol. Chem., 272 (1997) 9709-9719. 

Identified in bovine submaxillary mucin only, not in human /Kial-( — 4)- GlcNAc-( 1 — 3)- Gal... 

From references (60-8 l) a-GalNAc-(l — 6)-GalNAc is included for completeness, although so far this has been found only in bovine submaxillary mucin (82). All monosaccharides have the D-configuration when the structure has been identified in only one study, the source is identified. 

Porcine submaxillary mucins (100) Porcine (100) and bovine (101) submaxillary mucins... 

Canine submaxillary mucins (34) Glycopeptide hormones (99,109) Lysosomal hydrolases (110)... 

Griggs and coworkers studied hydrolysis with 3 M hydrochloric acid for 3 h at 100° of canine submaxillary mucin (CSM) and CSM mixed with a standard sugar mixture. Sugar recoveries were 76.0% for fucose, 76.6% for mannose, 84.3% for galactose, 82.5% for A -acetylglucosamine, and 87.7% for A -acetylgalactosamine. 

Griggs and coworkers studied the hydrolysis of canine submaxillary mucin (CSM) by 0.5, 3, and 6 M hydrochloric acid for 1.5, 3, 4.5, 6, and 24 h at 100°. They found that use of 3 M hydrochloric acid for 3 h gives the maximal release of neutral and amino monosaccharides, with the minimal degradation of the monosaccharides liberated, although recoveries of neutral monosaccharides were only 76-88%. Guerrant and Moss also used hydrolysis with 3 M hydrochloric acid, although for 16 h at 75°, for the hydrolysis of bacterial cell-walls. 

Neeser and Schweizer introduced 4 M CF3CO2H for 1 h at 121° for hydrolysis of glycoproteins. Both neutral and amino sugars were considered. They compared this method to hydrolysis with 0.6 M hydrochloric acid for 4 h at 100° and 3 M hydrochloric acid for 0.75 h at 125°. Hydrolysis of fetal-calf-serum fetuin, bovine submaxillary mucin, and horse-radish peroxidase showed hydrolysis with CF3CO2H to be superior. 

On the basis of the close correlation between the number of hydroxy-amino acids in bovine submaxillary mucin and the number of hexosamine and sialic acid residues, Hashimoto and Pigman (34) proposed that an O-glycosidic linkage was the only one that could be present in large amounts. Anderson et al. (38) reported a disappearance of much of the serine after incubation of the proteoglycan of chondroitin sulfate with alkali and suggested that this loss resulted from a -elimination reaction. 

Figure 7. The rate of cleavage of the main components of bovine submaxillary mucin by alkaline sodium borohydride at 45° C.

Pig submaxillary mucin (74) exists in two forms in individual glands one of these possesses A activity, and the other does not. Their gross compositions were identical. Five oligosaccharides were isolated, the largest having the structure... 

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