Mucus glycoprotein

Mucolytics reduce the viscosity of tenacious and purulent mucus, thus faciUtating removal. The distinction between mucolytics and other classes of expectorants is frequently blurred. Steam, sometimes in conjunction with surfactants or volatile oils, has long been used to decrease viscosity by physical hydration. However, agents that chemically depolymerize certain components of mucus are available. Trypsin and other proteolytic enzymes have shown good clinical activity because of their abiUty to cleave glycoproteins. Pancreatic domase, which depolymerizes DNA found in purulent mucus, also has shown clinical utihty. 

Several mucolytics reduce the viscosity of mucus by cleaving the disulfide bonds that maintain the gel stmcture. AJ-Acet l-L-cysteine [616-91 -1] (19), introduced in 1963, and mesna [19677-45-5] (20), developed in Europe in the early 1970s (20,21), are effective compounds in this class. Whereas most mucolytics must be adrninistered by aerosol, carbocysteine [638-23-6] (21), which contains a derivatized sulfhydryl group, has shown activity by the oral route (22,23). However, carbocysteine does not reduce mucus viscosity, as does acetylcysteine, but appears to have a direct action on mucus glycoprotein production (24). 

Mucus Viscous glycoprotein, proteoglycan secretion of goblet cells and... 

Mucus layer (glycoprotein gel, 90% oligosaccharide, implicated in pH microclimate) Unstirred water layer... 

Interacts with polar sites of glycoproteins in epidermal mucus of fish... 

Macrostructure of mucus glycoproteins in solution, 47, 345-381 Metal cations, complexes of, with carbohydrates in solution, 47, 1 -43 Molecular structure of lipid A, 50,211 -276 Monosaccharides, decomposition of, 47, 203-278... 

Carlstedt, I. and Sheehan, J. K. Stmctnre and macromolecnlar properties of cervical mucus glycoproteins. Symposia of the Society for Experimental Biology 1989, 43, 289-316. 

Carlstedt, I., Lindgren, H., Sheehan, J. K., Uhnsten, V, and Wingerup, J. Isolation and characterization of human cervical-mucus glycoproteins. Biochem J. 1983, 211, 13-22. 

Van Kooj, R. J., Kathmann, H. J. M., and Kramer, M. F. Human cervical mucus and its mucous glycoprotein during the menstrual cycle. Fertility and Sterility 1980, 34, 226-233. 

The sialic acid residues are usually in a terminal position on the carbohydrate chain, whereas the ester sulfate residues are in a more internal position both contribute to give the molecule a net negative charge. The molecular weights of mucus glycoproteins range from 0.5 to 16 X 10 Da [4]. 

Campbell, B.J., Biochemical and Functional Aspects of Mucus and Mucin-type Glycoproteins. In Bioadhesive Drug Delivery Systems (E. Mathiowitz, D.E. Chickering, lit, and C.-M. Lehr, eds.) Marcel Dekker, Inc., New York, 1999, pp. 85-130. 

Oral mucosae are covered with mucus which serves as a link between the adhesive and the membrane. Mucus is a glycoprotein consisting of a large peptide backbone with pendant oligosaccharide side chains. The side chains terminate in sialic or sulfonic acids, L-fucose, sulfated galactose, or A -acetylglucosamine. The glycoprotein component imparts the viscous or gel-like (non-Newtonian) nature due to its capacity... 

In industrialised societies, most gallbladder stones are mixed in composition. They contain not only cholesterol but also bile pigments, calcium salts, mucus glycoprotein and often amorphous material. Nonetheless, they are still described as cholesterol-rich although the arbitrary definition for cholesterol-rich stones varies from author to author ranging from >70% to >90% by weight. 

M. Kimura, Y. Hama, T. Sumi, M. Asakawa, R. B. N. Narasinga, A. P. Home, S.-C. Li, Y.-T. Li, and H. Nakagawa, Characterization of a deaminated neuraminic acid-containing glycoprotein from the skin mucus of the loach, Misgurnus anguillicaudatus, J. Biol. Chem., 269 (1994) 32138-32143. 

The hydrophilic properties of mucins, the large glycoproteins of mucus, are due to multiple O-linked glycosyl chains on these proteins. 

---