Mucin composition

For novel oligosaccharides for which H-n.m.r. data have not previously been documented in the literature, it is necessary to supplement the H-n.m.r. data with composition, sequence, and linkage information provided by chromatographic and m.s. analyses. An illustrative example is the characterization of the following oligosaccharide of the glycopeptides of fetal gastrointestinal mucins of meconium (74) ... 

A number of ocular surface disorders collectively termed as Dry Eye Syndromes have also been associated with the conjunctiva. For example, a deficiency and/or imbalance in compositions of the tear film is often found on the ocular surface during keratoconjunctivitis sicca. Since the conjunctiva plays a direct role in the maintenance of the tear fluid stability via secretion of mucin [1] by its resident goblet cells [4] and basal fluid secretion driven by electro-osmotic gradients across the tissue [3], the conjunctiva is a well deserved, but not intensively studied, target of interest in research efforts aimed against combating Dry Eye Syndromes. 

Akhtardzhiev, K. and D. Koley. 1961. Composition of mucins. II. Mucins from Malya sylyestris flowers. Pharm. Zentralh. 100 14-16. 

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... 

Some studies have been made relating specifically to astringency. Some of these studies have focused directly on interactions between tannins and salivary proteins [21, 23, 25, 46, 50-53], and on the changes in saliva protein composition after interaction with tannins [15, 38, 54, 55]. Other studies have correlated the sensorial astringency with protein-tannin interactions [45, 56, 57]. In fact, the astringency felt when sampling different tannin solutions can be correlated with the ability of these tannins to precipitate proteins. This effect has been observed with several proteins such as mucin [45], ovalbumin and gelatin [57], bovine semm albumin (BSA), and salivary proteins [58]. 

A review of analyses of the composition of mucus indicated that protein makes up 4—49% of the coral organism with total N making up 0.04—5.2% of mucus (Brown and BytheU, 2005). The primary constituents of the mucus matrix are glycoproteins or mucins. In a recent model of the mucus layer, organic exudates and organic N are released from the coral surface and go on to support a dynamic microbial community within the mucopolysaccharide layer around the coral (Rohwer and KeUey, 2004). 

In addition, steroid ulcer has been related recently to mucin deficiency caused by this therapy. Menguy and Masters injected steroids into rats with denen ated antral pouches (M28). They found substantially decreased mucus secretion, as well as compositional change of antral mucus characterized by decrease in its sialic acid concentration (Fig. 14). They concluded that the steroids interfered with the rate of the mucous barrier renewal, caused decreased mucus production, and lowered the threshold of gastric mucosal susceptibility to peptic digestion. Robert and his associates studied the relationship of the mucus secretion to the development of ulcers in fasting rats (R7), as well as in those given large doses of steroids (R8). They determined mucus content by quantitation of hexosamine and found decrease in concentration and output in rats who developed ulcers. The latter appeared only in that portion... 

The existence of more than one mucoprotein in the dissolved mucin fraction of the gastric juice was further substantiated in our laboratory (G26, G27, G36). We found (G27) that the composition of dissolved mucin varied markedly, depending upon the stimulus applied to gastric secretion. These variations included degree of hydration, extractability with 60% alcohol, and content of tyrosine, nitrogen, and reducing substances. We therefore postulated that, in man, at least two but probably three different mucous substances were present within the mixture of mucosubstances called dissolved gastric mucin (Gll, G27) (Fig. 16). 

When 1.5 volumes acetone is added to the trichloroacetic acid filtrate of the gastric juice, an abundant flocculent precipitate forms, which contains all the components of dissolved mucin with the exception of soluble mucus. If this precipitate is taken up in dilute alkali and then acidified with dilute HCl down to pH 3.5, a fine flocculent precipitate forms, which we named dissolved mucoprotein (G27, G36). It was later renamed glandular mucoprotein (G9, G38) because of its close relationship to the fundic glands of the stomach. This material contained much protein its nitrogen content was 12.61 0.44% and its tyrosine content 7.50 0.65% by the Folin-Giocalteu reaction. The reducing substance content was 6.38 1.48% before and 12.5% after hydrolysis (G9, G27, G36) (see Table 4). Werner (W9) determined the composition of this mucoprotein fraction and found that it contained 11.2% N by Kjeldahl, 8.8% hexosamine, 4.8% uronic acid, and 2.0% sialic acid. 

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