Current concepts of the structure and nature of mammalian salivary mucous glycoproteins

The visco-elastic properties of salivary secretions are due to high molecular-weight glyco-proteins, known as mucins. Mucins are composed of numerous oligosaccharide side-chains O-glycosidically linked through 2-acetamido-2deoxy-α-d-galactose to the hydroxyl groups of seryl and threonyl residues of the protein core; on the average, every fourth amino acid residue is involved in such a bond. This work conveys their isolation and purification, compiles the compositional analysis of several mammalian submaxillary and sublingual mucins; defines the conditions of the alkaline β-elimination reaction, its mechanism and importance in structural studies of glycoproteins, and briefly discusses the influence of stimuli on mucous secretions, as well as biosynthesis, structural diversity, and physiological role of salivary mucous glycoproteins.