MUCINS AND THEIR POTENTIALS

Mucins are the major macromolecular constituents of the mucous secretions that coat the oral cavity and the respiratory, gastrointestinal and urinogenital tracts of animal. They are responsible for the viscoelastic properties of the secretions, providing protection for the exposed delicate epithelial surfaces from microbial and physical injuries. Secretory mucins are typically of very high molecular mass (over 1 mDa) and have hundreds of O-linked saccharides constituting between 50% and 80% of the molecule by weight. The saccharides are based, at present, on seven core structures and can vary in length from disaccharides to oligosaccharides of approximated 20 monosacharides and exhibit astonishing diversity. The biological relevance of this diversity is not fully understood, but one possibility is that they act as ‘decoy’ receptors for the prevention from binding of pathogens to epithelial cell. It has been shown for a long time that the saccharides are linked to serine and threonine residues of the protein scaffold. However, owing to the technical problems associated with deglycosylation of mucins, the biochemical characterization of the protein backbone of the large discrete mucins has been fraught with difficulties.