Desialylation mucins

The action of sialidase also contributes to the liquification of muein barriers lining endothelia, as mentioned above for Acanthamoeba infeetion of the eye. This property is most relevant in tracheobronchial, intestinal and urogenital tracts [245,853], Often other hydrolases, mucinases , support the viscosity-decreasing effeet initiated by mere desialylation of mucins, as was observed with intestinal [854,855], vaginal [856] and other [857] bacteria, as well as with the flagellates Trichomonas vaginalis and T. foetus [858]. Microbial sialidase is considered a risk factor for intra-uterine infection and preterm birth [858]. 

On the basis of the structural identity of the newly formed oligosaccharide unit arising from the in vitro D-galactosylation of desialylized ovine sub-maxillary mucin, the porcine submaxillary gland galactosyltransferase has been defined as a UDP-D-galactose Q -D-2-acetamido-2-deoxygalactosyl-protein... 

A keratan-sulphate-degrading enzyme from Escherichia freundii has been shown to hydrolyse milk oligosaccharides and desialylized porcine colonic mucin for example, the tetrasaccharide (9) from milk and a reduced form thereof... 

Mucins.—Porcine colonic mucin has been desialylized by mild hydrolysis with acid the modified glycoprotein was used as a substrate for an endb-jS-D-galactosidase. ... 

An enzyme that degrades keratan sulphate, porcine colonic mucin, and milk oligosaccharides has been isolated from E. Desialylized, porcine colonic... 

Total sialic acid content was found to be lower in several SV40-transformed clones of Swiss 3T3 mouse cells (Ohta et aL, 1968). The plasma membrane as well as other membrane fractions of similar cell lines had reduced amounts of sialic acid (Wu et aL, 1969). Isolated plasma membranes from Py-BHK cells had 60% less sialic acid than membranes from normal BHK cells (Makita and Seyama, 1971). These changes appear to be associated with reduced sialyltransferase activities in the transformed cells. Grimes (1970) determined the levels of sialic acid and sialyltransferase activity in normal and SV40-transformed Swiss and Balb 3T3 mouse cells. There was a close correlation between sialic acid content and sialyltransferase activity in each cell line even though enzyme levels were measured with exogenous acceptors such as desialylated fetuin or bovine submaxillary mucin. This correlation has been extended to a number of other cell lines (Grimes, 1973). 

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