Ovomucoid avian

Other conversions to unnatural residues occur when most proteins are exposed to high pH (80, 81,82). The high pH causes a -elimination of a cystine (see Figure 16) or O-substituted serine or threonine, with the formation of a dehydroalanine or a dehydro-a-aminobutyrate. Such products are subject to nucleophilic attack by the e-amino group of a lysine to form a cross-linkage, such as lysinoalanine, or attack by cysteine to form lanthionine. Walsh et al. (81) have taken advantage of the formation of these cross-links to produce avian ovomucoids that have nonreducible cross-links and have lost the antiprotease activity of one of their two inhibitory sites (see Figure 17). 

In contrast to sero- and lactotransferrins, glycans of ovotransferrins from avian egg-white contain a bisecting A-acetylglucosamine residue, like other glycoproteins from oviducts, such as ovomucoid and ovalbumin for instance (Fig. 16A-C). Like all of the avian egg glycoproteins, ovotransferrins are not fueosylated. 

Empie, M.W. Laskowski, M. (1982). Thermodynamics and kinetics of single residue replacements in avian ovomucoid third domains effect on inhibitor interactions with serine proteinases. Biodtemistry, 21, 2274--84. 

Laskowski, M., Kato, 1., Ardelt, W. et al (1987). Ovomucoid third domain from 100 avian species isolation, sequences, and hypervariability of enzyme inhibitor contact residues. Biochemistry, 26, 202-21. 

Stehelia D, Varmus, H.E., Bishop, J.M. Vogt, P.K. (1976). DNA related to the transforming ger e(s) of avian sarcoma viruses is present in normal avian DNA. Nature, 260,170-3. Stein, J.P., Catterall, J.F., Kristo, P, Means, A.R. O Malley, B.W. (1980). Molecular cloning of the ovomucoid gerre sequences from partially purified messenger RNA Cell, 21, 681-7. 

C18H33NO15 503.456 Constit. of glycolipid from the spermatozoa of bivalve Hyriopsis schlegelii. Isol. from the acetolysis product of a sialogly-copeptide p obtd. by enzymatic hydrolysis of avian ovomucoid. 

Stevens, F.C. Feeney, R.E. Chemical modification of avian ovomucoids. Biochemistry 1963, 2, 1346-1352. 

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